我认为是d
didn't代表过去式
所以后面不能是“is”
宾语从句what后应用陈述句语序
具体分析：
1 宾语从句
一、什么是定语从句？
在复合句中，修饰某一名词或代词的从句叫做定语从句。在定语从句中，被修饰的这一名词或代词叫做先行词。在定语从句中的引导词叫做关系词。关系词又分关系代词和关系副词。
二、关系词有哪些？
1、关系代词：which（指sth），that（指sb或sth），who（指sb作主语或宾语），whom（指sb作宾语），whose（指sb或sth，作定语）
2、关系副词：when（指时间），where（指地点），why（指原因）
三、关系代词和关系副词有何区别？
主要是它们在从句中所起的作用不同。关系代词在从句中一般作主语或宾语。而关系副词在定语从句中作状语。分清楚这一关系并在做题时想着这个原则，就不会出原则性的错误了。
四、定语从句解题步骤
1、找对先行词。
2、确定先行词在定语从句中的位置，也就是在定语从句中担任何成份。这一点可以帮助我们划分使用关系代词还是关系副词。
eg：This is the place that/which I visited years ago.
This is the place where I lived years ago.
分析：这两句的先行词都是the place，由于第一句中的先行词在定语从句中作visit的宾语，所以选择关系代词，如果作宾语时关系代词可省略。而第二句的先行词则在定语从句中作状语，因为live是不及物动词，因此选择关系副词where。
3、区别各关系代词的使用。
五、关系代词中的which和that如何区分？
在先行词为物情况下，一般情况两者可通用，但也有不可互换的情况。
以下几种情况只用that:
1. 先行词all, everything, nothing, something, anything, little, much 等不定代词。
2. 先行词被all, every, no, some, any, little, much 等修饰。
3. 先行词被序数词或形容词最高级修饰时。
4. 先行词被the only, the very, the same, the last 修饰时。
That white flower is the only one that I really like.
This is the very book that I want to have.
The last place that we visited was the chemical works.
5. 有两个或两个以上的分别表示人和物的先行词，从句应用that,而不是其他。
He talked about the teachers and schools that he had visited.
6. 当主句是以who, which 开头的特殊疑问句时，定语从句多用that，而不用who(whom)，which.
Who is the person that is standing at the gate?
以上通常是使用于物，人一般不受限制，但如果正式和严谨可以遵循这一原则。
六、各关系副词
when：I did remember the day when I come to No. 4 High School.
where：This is the house where I lived years ago.
why：Could you please tell me the reasons why you came late to school this morning.
七、几点说明
1、在先行词为人的情况下，遇到who和 that都有的情况，如何处理？
答：如果句中已有who的情况下为避免重复，用that。
eg：Who is the girl that is speaking to my teacher?
2、在先行词为人且在定语从句中作宾语，用who还是whom？
答：一般情况两者可通用，但遇到介词提前时只能用whom。
eg：He is my English teacher from whom I learned a lot.
定语从句练习
一、填空
选择正确的关系代词填入题目中的空白处。
1. This is the comrade __________ will go to the south with us tomorrow.
2. Who's the student __________ the teacher is talking with?
作者： 漫步在雨天 2006-6-4 13:43 回复此发言
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2 宾语从句
3. I like the present __________ you've sent to me.
4. The nurse __________ we talked about can speak English well.
5. This is the most difficult job __________ we've ever done.
6. This is the cleverest man __________ I've ever known.
7. I bought all __________ was necessary.
8. The old gentleman __________ you met just now is a famous writer.
9. The girl to __________ I lent my bike works in a hospital.
10. All __________ come are welcome.
11. This is the girl __________ songs you heard last night.
12. She was the brave girl __________ name is known to everybody here.
13. Thank you for the help __________ you've done for me.
14. This radio set __________ we have had for two years is a good one.
15. The next question __________ I found difficult to answer was put to me by Mary.
二、将下列句子合并成带有定语从句的复合句。
16. He is the young writer．He wrote the book．
17．Do you know the doctor?
He comes here once a month and examines the workers．
18．The foreign guest is Mr．Green．
You saw him at the school gate．
19．He is the new head．
I was talking about him this morning．
20．I've received the book．
Father sent it to me．
21．The factory has got one success after another．
We visited the factory last week．
22．What's the name of the girl?
Her grandpa took part in the Long March．
23．The man looks like the actor．
I've heard his songs on TV．
24．This letter is from my elder brother．
He serves in the army．
25．Do you see the bridge?
It was built last year．
26．The old man is a professor．
He teaches chemistry in a college．
27．We visited the singer yesterday．
Her performances we all like very much．
28．The old worker is still working hard with us．
His hair has turned gray．
29．The bike was not good．
You wanted to buy it．
30．The medicine didn't help me．
Dr．Chang had given it．
31．The exercise is wrong．
We did it last night．
32．The woman is here now．
You were talking about her．
33．The bus was the wrong one．
Xiao Li was running after it．
34．The wallet has been found．
Mr．Hopkins was looking for it．
35．The recorder has been stolen．
Wang spent all the money on it．
答案
1. who/that 2. that 3. that/which 4. whom/that 5. that
6. that 7. that 8. whom/that 9. whom 10. that
11. whose 12. whose 13. which/that 14. which/that 15. that
16. He is the young writer who wrote the book.
17. Do you know the doctor who comes here once a month and examines the workers?
18. The foreign guest whom you see at the school gate is Mr. Green.
19. He is the new head whom I was talking about this morning.
20. I've received the book which father sent to me.
21. The factory which we visited last week has got one success after another.
22. What is the name of the girl whose grandpa took part in the Long March?
23. The man looks like the actor whose songs I've heard on TV.
24. This letter is from my elder brother who serves in the army.
25. Do you see the bridge which was built last year?
26. The old man who teaches chemistry in a college is a professor.
27. We visited the singer yesterday whose performances we all like very much.
28. The old worker whose hair has turned grey is still working hard with us.
29. The bike which you wanted to buy was not good.
30. The medicine which Dr. Chang had given didn't help me.
31. The exercise which we did last night is wrong.
32. The woman whom you were talking about is here now.
33. The bus which Xiao Li was running after is the wrong one.
34. The wallet which Mr. Hopkins was looking after has been found.
35. The recorder on which we spent all our money has been stolen.
作者： 漫步在雨天 2006-6-4 13:43 回复此发言
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3 回复：宾语从句
【注意】①有的动词可接双宾语，间接宾语指人，直接宾语指物。这类动词常见的有：give，buy，lend，pass， tell，leave等。如：
He bought me a book．
Pass me the ball，will you？（间宾＋直宾）
直接宾语一般放在间接宾语之后，但若把直接宾语放在前面，则要在间接宾语前加适当的介词如to或 for等。如：
Han Chen lent some money to Li Hai．（直宾＋间宾）
Xiao Liu bought a dictionary for Tom．（直宾＋间宾）
②有的动词常用不定式作宾语，而不能用动名词。这类动词有：want，wish， hope，promise，decide，agree， choose，care等。如：
I hope to see you again．
③有的动词一般只用动名词作宾语，而不用不定式。这类动词有：enjoy，finish，mind，practise，miss， suggest，keep（on）等。如：
Do you mind my opening the window？
④有的动词后接不定式与动名词含义不同。
a）forget to do表示“未发生的动作”，forget doing表示“已完成的动作”。如：
Don't forget to come here earlier tomorrow．（还没来）
I forgot returning the book to him．（书已还给他了）
b）stop to do（不定式为状语）表示“停下
原来的事，去做另一件事”，stop doing表示“停止做某事”。如：
I stopped to talk with him．（我停下来与他谈话。）
The students stopped talking when the teacher came in．（老师进来时学生们停止谈话。）
4．定语：用于修饰名词或代词，一般由形容词、名词、数词、不定式等充当。如：
What a beautiful kite it is！（形容词）
She is a chemistry teacher．（名词）
There are two students in the classroom．（数词）
We have something to do tomorrow．（不定式）
The man in blue is my brother．（介词短语）
【注意】定语一般位于被修饰词之前，但若修饰不定代词或不定式等短语作定语，则放在后面。
5．状语：用于修饰动词、形容词、副词或全句，一般由副词、介词短语、不定式短语或从句充当。单个副词作状语一般放在被修饰词之前，短语或从句放在句首或句末。如：
Thank you very much．（副词）
I get up at five in the morning．（介词短语）
He is studying hard so as to catch up with others．（不定式短语）
We were having breakfast when the telephone rang．（从句）
【注意】enough作状语只能放在被修饰词之后。如：
He is old enough to go to school．
6．表语：用于说明主语的身份、特征或感受，一般由名词、数词、形容词、分词等充当。常用的连系动词有：be，look，get，sound（听起来），feel，become， smell，turn，taste（尝起来）等。如：
They are workers．（名词）
Two and three is five．（数词）
The story is very interesting．（形容词）
M y job（工作）is teaching English．（动名词）
She is at home．（介词短语）
I feel terrible．（形容词）
The dish tastes delicious．（形容词）
7．宾语补足语：用于补充说明宾语的动作，一般位于宾语之后，宾语与宾语补足语一起构成复合宾语。需接复合宾语的动词有：tell，let，help，teach， ask，see，have，order，make等。“宾补”一般由不定式短语、分词、名词、形容词等充当。如：
We elected him monitor．（名词）
I found it difficult to learn English well．（形容词）
The doctor told me to do more exercise．（不定式短语）
He is going to have his hair cut．（过去分词）
They saw a bird flying in the sky．（现在分词）
【注意】有的动词后若用不定式作其“宾补”则需要省略to。这类动词有： make，let，have，see，feel，hear，watch，notice，listen to，look at等。如：
I listened to them sing yesterday evening．
Ling Feng made the baby laugh．
参考资料：百度贴吧