When the direct testimony is based upon eyewitness observations, cross-examination that is directed at witness credibility, veracity, and perception may be useful means of testing the truth of the specific factual assertions.

• 当直接证言是建立在目击证人的观察上时，针对证人的可信程度、真实准确性及其认识的反诘问即会是有用的手段以检验具体的事实断言的真实性。