why 后不能跟名词,只能跟助动词,be动词、情态动词j及从句. 如：Why are you laughing?你们为什么笑? Why didn't you stop him?你为什么不阻拦他呢? Why (not) turn off the gas?为什么（不）要把煤气关掉? Why he did that is not known. 他为什么做那件事,谁也不知道.
why 后不能跟名词,只能跟助动词,be动词、情态动词j及从句. 如：Why are you laughing?你们为什么笑? Why didn't you stop him?你为什么不阻拦他呢? Why (not) turn off the gas?为什么（不）要把煤气关掉? Why he did that is not known. 他为什么做那件事,谁也不知道.