Question

【題目】 Luggage may not be brought into the building ________ a guard has checked it first.

A. when B. because C. after D. unless

Answer 1

【答案】D

【解析】

試題分析：考察條件狀語從句引導(dǎo)詞。A. When當(dāng)… 引導(dǎo)時(shí)間狀語從句；B. Because因?yàn)?/span> 引導(dǎo)原因狀語從句；C. after 在…之后D. Unless除非 引導(dǎo)條件狀語從句。該句意思為：除非保安檢查過行李，否則不能帶入這棟建筑物。保安檢查行李是條件，所以這是個(gè)條件狀語從句，根據(jù)句意故選D