Question

【题目】The government calls on us to avoid visiting crowded areas and medical institutions _______ it is necessary.

A.whileB.becauseC.unlessD.when

Answer 1

【答案】C

【解析】

考查条件状语从句。句意：政府呼吁我们避免访问拥挤的地区和医疗机构，除非有必要。A. while然而，当……时候；B. because因为；C. unless除非；D. when当……时候。由语境可知，it is necessary表条件，所以用unless引导条件状语从句。故选C项。