You will be out of date ____ you keep on studying from time to time.

题目

You will be out of date ____ you keep on studying from time to time.
A)if B)unless C)because D)or

答案

A)if
IF 引导的条件状语从句中用一般现在时代替一般将来时.
“如果你一直不停的学习,你会过时的.”