Question

(2013·甘肃兰州名校高三检测)The professor told me to start the research right now, ________ I was sure to fall behind.

A．or

B．so

C．but

D．and

Answer 1

A

A　句意：教授让我立刻开始研究工作，否则我肯定会落后的。根据句意选用or，意为否则。