things like transport，irrigation，electricity and schools.

A.which B.that

C.where D.what

答案　D　[句意：一个国家的基础设施是让一切顺利运行的事物，包括像交通、灌溉、电力以及学校等方面。空处引导表语从句，且从句中缺少主语，所以应用连接代词what来引导该表语从句。]

6.Inner sunshine warms the heart of not only the owner，but all ________ come in contact with it.(2018·江苏省四星级学校4月联考)

A.that B.which

C.what D.whom

答案　A　[句意：内心的欢乐不仅温暖了欢乐者自己的心，也温暖了所有与之接触的人的心。分析句子结构可知，空处在此引导定语从句，且在从句中作主语，先行词是不定代词all，指人，故只能用that。]

7.The drug is not harmful itself，but is dangerous，according to the new finding，if ________ with alcohol.

A.taking B.being taken

C.to take D.taken

答案　D　[句意：根据新的发现，该药本身并无害处，但若与酒一同服用则有危险。分析句子结构可知，The drug和take之间是逻辑上的动宾关系，故应用其过去分词形式。]

8.Professor White believes as soon as Cathy learns the office ________ she will be an excellent assistant.

A.dilemma B.routine

C.schedule D.principle

答案　B　[句意：怀特教授相信凯西一旦熟悉了办公室的日常事务，她就会成为一名优秀的助手。dilemma "(进退两难的)窘境，困境"；routine "常规，例行公事"；schedule "工作计划，日程安排"；principle "原则，法则"。]

9.Over the past five years，the Chinese government ________ addressing PM2.5，which is the most critical pollutant for public health.(2018·江苏省高三第二学期