Question

He was told that it would be at least three months ___ he could recover and return to work.

A．when

B．before

C．since

D．that

Answer 1

B

before引導時間狀語從句，意為“在……之前”，表示他康復重返工作還至少三個月時間。when引導時間狀語從句，意為“當……的時候”。since引導時間狀語從句，意為“自從”，表示從某個時候一直延續(xù)到現在，常與現在完成時連用。that用于名詞性從句或定語從句。