英语高手+好人进！！问一个英语问题，在线等~~谢谢，答得好还会加分

解析：这句话的意思是你认为他会让谁写这封给老师的祝贺信.句子用到的语法是have sb do sth 由于前面提问的是whom,所以have sb do sth 中的sb就是whom所以得选择动词原形write.
你认为他会给哪个老师写祝贺信？的译文是：
Which teacher do you think he would write a letter of congratulation to?

这个应该是have sb. do sth的固定搭配。意思是让某人做某事。例如，I had my hair cut. 意思是我（让别人）理发了。还有一个典型的例子是我（让别人给我）照了张相。
根据朗文高阶英语词典的第五条和第六条，

[Cn.i no passive 不用於被动语态] order or arrange (that sb does sth) 命令或安排（某人做某事）: I`ll have the gardener plant some trees. 我要让园丁种些树. * Have the driver bring the car round at 4. 让司机4点钟把汽车开来.
(a) (used with a n + past participle 与名词+过去分词连用) cause sth to be done 使某事物予以处理: Why don't you have your hair cut? 你为什麽不理发? * They're going to have their house painted. 他们准备把房子粉刷一下. * We're having our car repaired. 我们的汽车正在修理. (b) (used with a n + past participle 与名词?过去分词连用) suffer the consequences of another person's action 承受、 蒙受他人行为之后果: He had his pocket picked, ie Something was stolen from his pocket. 他的口袋被掏了（衣袋中有东西被窃）. * She's had her wallet taken. 她的钱包被人拿走了. * Charles I had his head cut off. 查理一世遭斩首.

至于另外一句话应该翻译为Witch teacher do you think he would write a congratulation letter to?

1,Whom do you think he would(A) a letter of congratulation to the teacher?谁做你认为他会写贺信给老师？
2,Whom do you think he would(B)letter of congratulation to the teacher?谁做你想他会写来贺信的老师吗？
3,Whom do you think he would (C) a letter of congratulation to the teacher?谁做你认为他会写一封贺信给老师？
4Whom do you think he would (D) a letter of congratulation to the teacher?谁做你认为他会写贺信给老师？

这句话的意思是你认为他会让谁写这封给老师的祝贺信.句子用到的语法是have sb do sth 由于前面提问的是whom,所以have sb do sth 中的sb就是whom所以得选择动词原形write.