Question

You should study harder______ it is too late to catch up.

A．if

B．when

C．after

D．before

Answer 1

D

试题分析：if是否，如果；when当……时；after在……之后；before在……之前，以免。句意：你应该努力学习，不然太晚了，就来不及了。故选D。