题目内容：

Student are told _____ very careful when they are doing experiments.
A should be B.be C. to be D.will be
为什么选C,理由一定要详细.
tell sb sth 为什么这里用to be

优质解答

不定式从句,tell sb to do sth,告诉某人去做某事.这题是被动语态,所以就是 are told to do!