Youmustkeeponworkingintheevening

問題詳情：

You must keep on working in the evening________you are sure you can finish the task in time.

A．as                                                      B．if

C．when                                                 D．unless

【回答】

D　本題考查連詞的用法。unless意為“除非……(否則)”，引導狀語從句。根據句意可知應選D項。

知識點：連詞

題型：選擇題