____ you tell me what has happened?

____ you tell me what has happened?
A、May
B、Must
C、Can
D、Could
【正确答案】：D
【题目解析】：D 这里could表示请求,语气比较舒缓A 是指将来的B must 肯定是错的,问别人发生了什么事,怎么能用这么强烈的语气C can能,预期比could 稍强烈,所以也不适合.