The defendant assigns as error the denial of her timely motion for judgment as of nonsuit on the charge of second degree murder. The State does not contend that defendant’s gun inflicted the injuries resulting in her husband’s death; rather, it contends that she aided and abetted Tom Richardson in the murder of her husband. Before the jury could find the defendant guilty of second degree murder, the State first had the burden of offering evidence from which the jury in this case could find that Tom Richardson had committed the crime of second degree murder.
The evidence introduced by the State was clearly sufficient to support a finding by the jury that Tom Richardson shot and killed defendant’s husband with malice, and without just cause, excuse, or justification. State v. Moore, 275 N.C. 198, 166 S.E. 2d 652 (1969) ; State v. Banks, 143 N.C. 652, 57 S.E. 174 (1907) ; State v. Currie, 7 N.C. App. 439, 173 S.E. 2d 49 (1970).
Although the evidence is sufficient for the jury to find that Richardson committed the offense of second degree murder as a principal in the first degree, this conclusion does not put an end to our inquiry. Our concern is whether the evidence is sufficient to raise an inference that the defendant aided and abetted Richardson and whether the evidence will support the verdict that the defendant is therefore guilty as a principal in the second degree.
“The mere presence of a person at the scene of a crime at the time of its commission does not make him a principal in the second degree; and this is so even though he makes no effort to prevent the crime, or even though he may silently approve of the crime, or even though he may se*431cretly intend to assist the perpetrator in the commission of the crime in case his aid becomes necessary to its consummation.
To constitute one a principal in the second degree, he must not only be actually or constructively, present when the crime is committed, but he must aid or abet the actual perpetrator in its commission. A person aids or abets in the .commission of a crime within the meaning of this rule when he shares in the criminal intent of the actual perpetrator, and renders assistance or encouragement to him in the perpetration of the crime. While mere presence cannot constitute aiding and abetting in legal contemplation, a bystander does become a principal in the second degree by his presence at the time and place of a crime where he is present to the knowledge of the actual perpetrator for the purpose of assisting, if necessary, in the commission of the crime, and his presence and purpose do, in fact, encourage the actual perpetrator to commit the crime.” State v. Birchfield, 235 N.C. 410, 413-14, 70 S.E. 2d 5, 7-8 (1952) (citations omitted).
To sustain a conviction of the defendant as principal in the second degree, the State’s evidence must be sufficient to support a finding that the defendant was present, actually or constructively, with the intent to aid the perpetrator in the commission of the offense should his assistance become necessary and that such intent was communicated to the actual perpetrator. Such communication of intent to aid, if needed, does not, however, have to be shown by express words of the defendant, but may be inferred from his actions and from’his relation to the actual perpetrator. State v. Rankin, 284 N.C. 219, 223, 200 S.E. 2d 182, 185 (1973).
 Applying the foregoing well-established principles to the facts before us, we are of the opinion that the evidence is insufficient to raise an inference that defendant aided and abetted Richardson in the murder of her husband. While the evidence of the lover relationship between the defendant and Richardson and of defendant’s conduct both before and after the shooting of her husband are strong circumstances from which the jury might infer that the defendant intended to kill her husband, or that she silently approved of Richardson’s committing the act, or that she might have intended secretly even to aid him if such became necessary, there is nothing in the *432evidence from which the jury might infer that the defendant shared Richardson’s criminal intent to kill her husband. This is true since there is no evidence in the record from which the jury could find that the defendant knew that Richardson would come suddenly upon the immediate scene of her altercation with her husband and fire four shots at point blank range at her husband, or that the defendant by word or deed communicated any intention she might have had to Richardson which he might have considered as encouragement to him to commit the crime.
Under the circumstances here presented, the defendant had no control over her presence at the scene of the killing of her husband within the contemplation of the rule of law applied in State v. Birchfield and State v. Rankin, supra. No construction of the evidence here will permit an inference that the defendant had any knowledge that Richardson might get out of her automobile and shoot and kill her husband. In the absence of some evidence that the defendant had some knowledge, either actual or constructive, that Richardson intended to shoot her husband, the defendant could not have shared his criminal intent to commit the crime. The assignment of error is sustained.
 The defendant assigns as error the denial of her motion for judgment as of nonsuit as to the charge of assault with a deadly weapon with intent to kill resulting in serious bodily injury. The uncontradicted evidence shows that the defendant carried the gun with her when she went back to the truck and later shot her husband, inflicting physical injury. There was in addition evidence that the injury could have caused permanent impairment. Clearly, the evidence was sufficient to require submission of this case to the jury and would support the conviction for assault with a deadly weapon inflicting serious injury.
 Defendant assigns as error the refusal of the court to instruct the jury on the doctrine of self-defense as to the felonious assault charge. A person is justified in defending himself if he “ ... is without fault in provoking, or engaging in, or continuing a difficulty with another . ” State v. Anderson, 230 N.C. 54, 56, 51 S.E. 2d 895, 897 (1949). Where the jury finds that the defendant intended to kill and inflicted injuries, to be completely absolved, the jury must find that he acted in self-defense against “actual or apparent danger of death or great bodily harm . . . . ” State v. Anderson, supra at 55, 51 S.E. 2d at 897. But, where the jury finds that the defendant did not intend to kill, the defendant “ ... is privileged by the.law *433of self-defense to use such force against the other as is actually or reasonably necessary under the circumstances to protect himself from bodily injury or offensive physical contact at the hands of the other, even though he is not thereby put in actual or apparent danger of death or great bodily harm.” State v. Anderson, supra at 56, 51 S.E. 2d at 897. Under either finding, though, the defendant must be without fault and must have acted in response to some danger of injury, either real or apparent.
The trial court is required to charge on self-defense, even without a special request, when, but only when, there is some construction of the evidence from which could be drawn a reasonable inference that the defendant assaulted the victim in self-defense. State v. Goodson, 235 N.C. 177, 69 S.E. 2d 242 (1952) ; State v. Moses, 17 N.C. App. 115, 193 S.E. 2d 288 (1972). No construction of the evidence here, in our opinion, gives rise to an inference that the defendant was in such danger, either real or apparent, as would justify acting in self-defense. This assignment of error is overruled.
 Defendant assigns as error the refusal of the trial judge to admit testimony of “prior threats the victim had made against the defendant,” or testimony as to the “victim’s reputation as a violent and dangerous fighting man.” Where there is other evidence of self-defense, testimony of threats and of the victim’s reputation are relevant in certain circumstances and generally admissible; but where there was no other evidence of self-defense, there was no prejudicial error in refusing to allow such testimony. Stansbury’s, North Carolina Evidence 2d, Vol. 1, §§ 106, 162(a) ; State v. Minton, 228 N.C. 15, 44 S.E. 2d 346 (1947); Nance v. Fike, 244 N.C. 368, 93 S.E. 2d 443 (1956).
 Defendant assigns as error the trial court’s action in sustaining the District Attorney’s objections to the following three questions asked to State’s witness Terry Wayne Brewer on cross-examination :
(1) “At any time did you see her [defendant] do anything to assist Tom Richardson in firing his four shots?”
(2) “When she [defendant] said this statement [where she told her husband she would kill him], did you catch every word that she said?”
(3) “O.K. Did William Lewis, was there enough room for that truck that was behind the car to have pulled out and gone straight down Highway 421 ?”
*434The judge is in charge of the scope of the cross-examination and we. are not inclined to review his decisions unless the defendant has shown an abuse of that discretion. State v. Lindley, 23 N.C. App. 48, 208 S.E. 2d 203 (1974), affirmed 286 N.C. 255, 210 S.E. 2d 207 (1974). The questions asked call for a conclusion on the part of the witness’. As such they were objectionable and the judge’s ruling was not an abuse of his discretion. This assignment of error is overruled. •
 By assignments of error IV and V, the defendant maintains the trial judge expressed an opinion on the evidence in violation of G.S. 1-180 by “sustaining his own objections throughout the trial” and in “cross examination of the defendant by the trial judge and comments by him as to her credibility.” “It is well settled in this State that the trial judge can ask.questions of a witness in order to obtain a proper understanding and clarification of the witness’ testimony. State v. Humbles, 241 N.C. 47, 84 S.E. 2d 264; State v. Stevens, 244 N.C. 40, 92 S.E. 2d 409; State v. Furley, 245 N.C. 219, 95 S.E. 2d 448.” State v. Strickland, 254 N.C. 658, 661, 119 S.E. 2d 781, 783 (1961). Similarly, “ . . . judges do not preside over the court as moderators, but as essential and active factors or agbneies in the due and orderly administration of justice.” Eekhout v. Cole, 135 N.C. 583, 589, 47 S.E. 655, 657 (1904) ; State v. Colson, 274 N.C. 295, 308, 163 S.E. 2d 376, 385 (1968). The court has authority to limit examination and to exclude evidence which is wholly incompetent or inadmissible. Greer v. Whittington, 251 N.C. 630, 111 S.E. 2d 912 (1960).
- We have carefully examined each of the 15. exceptions upon which these assignments of error are based and find them to be without .merit. The able judge did not sustain his own objections as contended by defendant, nor did he cross-examine defendant, or make comments about her credibility. The record discloses that the defendant on both direct and eross-exámination repeatedly gave answers that were not responsive and testimony that was not clear. Each ruling, question, or comment challenged by these exceptions clearly was for the purpose of clarifying defendant’s testimony or was a proper exercise of the judge’s discretion in controlling the examination of the witness. These assignments of error are overruled.
The defendant has additional assignments of error with respect to the charge of second degree fnurder which we do not discuss in view of our disposition of the charge.
*435The result' is: With respect to the charge of assault with a deadly weapon with intent to kill inflicting serious injury, we hold that the defendant had a fair trial free from prejudicial error..
With respect to the charge of second degree murder, the evidence was insufficient to support a verdict of guilty, and the defendant’s motion for judgment as of nonsuit should have been allowed. Hence, the judgment entered on the charge of second degree murder is
Judges Morris and Arnold concur.