1.Modern science has given clear evidence ________ smoking can lead to many diseases.
A. what B. which
C. that D. where
[解析]本题考查同位语从句的引导词。从句结构完整，并且对 evidence 的内容起到了补充说明的作用，故应用 that 引导该从句。句意：现代科学提供了明确的证据表明吸烟能导致很多疾病。
[答案]C
2.His writing is so confusing that it's difficult to make out ________ it is he is trying to express.
A. that B. how
C. who D. what
[解析]本题考查名词性从句。句意：他的书写得这么乱，很难弄明白他想要表达什么。what 引导宾语从句，并在从句中作表语。
[答案]D
3.The villagers have already known ________ we'll do is to rebuild the bridge.
A. this B. that
C. what D. which
[解析]本题考查名词性从句。句意：村民们已经知道我们将要做的事情是重建桥梁。know 后面跟宾语从句，从句中缺少 do 的宾语，表示“做……的事”，故用 what 引导宾语从句。this 不引导从句;that 引导宾语从句时不作成分;which 引导宾语从句时有疑问的意思，意为“哪一个”。
[答案]C
4.Before a problem can be solved, it must be obvious ________ the problem itself is.
A. what B. that
C. which D. why
[解析]本题考查名词性从句的引导词。句意：在一个问题被解决之前，必须弄清问题本身所在。在 It must be obvious ________ the problem itself is.这一句中，it 为形式主语，________ the problem itself is 是真正的主语从句，从句中缺少表语，故用 what 引导。
[答案]A
5.Our teachers always tell us to believe in ______ we do and who we are if we want to succeed.
A. why B. how
C. what D. which
[解析]本题考查名词性从句。句意：老师总是告诉我们，如果想要成功，要相信自己所做的事情，也要相信自己。what 引导名词性从句，同 something that，补充前后主从句所缺失的成分。
[答案]C
6.________ Barbara Jones offers to her fans is honesty and happiness.
A. Which B. What
C. That D. Whom
[解析]本题考查主语从句的引导词。句意：芭芭拉·琼斯提供给她的粉丝们的是诚实和快乐。which 引导主语从句时有选择的意思，意为“哪一个”;what 引导主语从句，在从句中作 offer 的宾语，意为“……的人或事”;that 引导主语从句时不作成分;whom 引导主语从句时在从句中作宾语指人。本题中主语从句中缺少 offer 的宾语，表示“……东西”，故用 what 引导。
[答案]B
7. I'd like to start my own business—that's ________ I'd do if I had the money.
A. why B. when
C. which D. what
[解析]本题考查名词性从句的引导词。句意：我想创办自己的生意——那就是如果我有钱的话我想做的事。分析句子结构可知，空白处需要连接代词引导表语从句，首先排出A、B两项的连接副词;另外，which 意为“哪一个，哪一些”，不合题意，what 意为“……的事”，符合题目要求，在句中作 do 的宾语。
[答案]D
8.We've offered her the job, but I don't know ________ she'll accept it.
A. where B. what
C. whether D. which
[解析]本题考查宾语从句的引导词。句意：我们已提供她工作，但我不知道她是否会接受。根据句子结构，本题为宾语从句，且从句中不缺少句子成分，故应用连词 whether。而 where 在从句中作地点状语;what，which 在从句中作宾语，故C项正确。
[答案]C
9.It was never clear ________ the man hadn't reported the accident sooner.
A. that B. how
C. when D. why
[解析]本题考查名词性从句。句意：那个人为什么没有早报告这起交通事故还不清楚。分析结构可知，it 作形式主语，真正的主语为后面的从句。又由句意可知此处主语从句用 why 引导，故D项正确。
[答案]D
10. Before the sales start, I make a list of______ my kids will need for the coming season.
A. why B. what
C. how D. which
[解析]句意：在促销活动开始之前，我列出了一份在即将来临的季节里孩子们所需物品的购物清单。
[答案]B
11.We should respect food and think about the people who don't have ______ we have here and treat food nicely.
A. that B. which
C. what D. whether
[解析]句意：我们应当重视食物，珍惜食物，并应为那些没有我们所拥有的食物的人们做些考虑。that 引导名词性从句时不作句子成分，而此处引导词须作宾语，故 that 不合适;which 和 whether 的含义与句意不符;what 引导宾语从句并在句中作宾语，符合句意。
[答案]C
12. As a new graduate, he doesn't know______ it takes to start a business here.
A. how B. what
C. when D. which
[解析]句意：作为一名新毕业生，他不知道创业需要什么。it take sth. to do sth.，“花费/需要……干某事”。本题考查宾语从句，且从句中 take 缺少宾语，故用 what。
[答案]B
13. I want to be liked and loved for ________ I am inside.
A. who B. where
C. what D. how
[解析]句意：我想让人们因为我的内在本质而喜欢我爱我。此题考查宾语从句，what 此处表示“……的内容/事情”，相当于“the thing(s) that”，在从句中作表语。
[答案]C
14.We haven't discussed yet ________ we are going to place our new furniture.
A. that B. which
C. what D. where
[解析]句意：我们还未讨论买的新家具将放在什么地方。where 引导宾语从句，并在从句中作地点状语。
[答案]D
15.—Have you finished the book?
—No, I've read up to ________ the children discover the secret cave.
A. which B. what
C. that D. where
[解析]句意：—你读完这本书了吗?—没有，我读到孩子们发现秘密洞穴的地方。考查 where 引导的宾语从句，作介词 to 的宾语。
[答案]D
16. How much one enjoys himself travelling depends largely on ________ he goes with, whether his friends or relatives.
A. what B. who
C. how D. why
[解析]句意：一个人在旅游中玩的高兴程度在很大程度上取决于他是和谁一起去的，是他的朋友还是亲戚。介词 on 后跟宾语从句，从句中缺少介词 with 的宾语，用关系代词，排除C、D;由句意知应用 who。
[答案]B
17.It is uncertain ________ side effect the medicine will bring about, although about two thousand patients have taken it.
A. that B. what
C. how D. whether
[解析]句意：尽管大约2,000名患者已经服用了这种药，但是它会带来什么样的副作用还不清楚。因为受 it is certain/uncertain that... 句型的影响，很多同学易误选 that，但此句中空格处的词不但引导真正的主语从句，还要作从句的宾语，即 bring about 的宾语，起双重作用，只能选择 what。how 与 whether 无论是词义还是担当的成分都不符合要求。
[答案]B
18.Cindy shut the door heavily and burst into tears. No one in the office knew ________ she was so angry.
A. where B. whether
C. that D. why
[解析]句意：Cindy 用力关上门并且大哭了起来。办公室里没人知道她为什么那么生气。分析结构可知，________ she was so angry 作 knew 的宾语，由句意可知，此处应填一个表示原因的连接副词，故应选 why。
[答案]D
19.To improve the quality of our products, we asked for suggestions ________ had used the products.
A. whoever B. who
C. whichever D. which
[解析]句意：为了提高我们的产品质量，我们向任何使用过我们产品的人征求意见。asked 的宾语已经后置，即 whoever had used the products，其中 whoever 相当于 anyone who。
[答案]A
20.Many young people in the West are expected to leave ________ could be life's most important decision—marriage—almost entirely up to luck.
A. as B. that
C. which D. what
[解析]句意：许多西方年轻人都把人生中最重要的决定——婚姻——几乎都归因于运气。句中 what could be life's most important decision—marriage 作 leave 的宾语。what 在宾语从句中既起连接词的作用，又在句中充当主语。
[答案]D
