Question

【题目】Why are you here? You are supposed to ________ the experiment in the lab.

A. perform B. be performing C. have performed D. be performed

Answer 1

【答案】B

【解析】考查时态。句意：你为什么在这里？你应该正在实验室里做实验。表示“正在做某事”用进行时态，故选B项。