Studies support the theory that there are several causes, instead of a single environmental cause or genetic problem.

VOA: special.2009.01.06

Don't just stop in the middle of the street because everyone is coming right behind, and it's going to cause a problem.

请不要停留在街道中央，因为街上人来人往，
你的停留是会惹麻烦的。

在纽约的感受 - SpeakingMax英语口语达人