When will your father be back from work?____9.00.He is busy with his work these days.

问题描述:

When will your father be back from work?____9.00.He is busy with his work these days.
A.Until B.Not until C.Before D.Not after

【B】
符合语境表示很忙,不到九点回不了家那为什么不选A因为直到9点以前,他都没有回家,是否定的。用not until。如果直到9点以前,他都在家里,然后才出去工作,那么9点以前他在家就是肯定的,用until