1.I am afraid you are wrong.这是什么从句?
答：I am afraid of sth.sth.作 be afraid of的宾语（介词of的宾语）,这个宾语如果是一个名词性从句（that 从句）,则省略介词of:I am afraid that you are wrong.口语中这个that也省略.所以本质上you are wrong是名词性从句.
2.My ambition is to become part of the national team.为什么part of 前面不加a?
答：a是一个小词,在讲a part of ...时,常可以省略,因为在念它的时候,本身就似有似无.
3.I used to climb trees.这里的不定式做什么成分?
答：一般将used to与ought to 一样看作情态动词.
4.The doors should be wide enough for a person to enter.这里的不定式做什么成分?
答：这里的for a person to enter 是不定式的复合结构.在句子中作状语.
5.I have a chance to say.这里的不定式做什么成分?
答：与have sth.to do 一样,不定式作后置定语.
6.I am happy to see you.这里的不定式是做状语吗?
答：是的.可以认为是原因状语.
7.I persuade her that he is right.这个谓语后有her也属于宾语从句吗?
答：这里的persuade 是双宾用法,即her是间接宾语,that从句是直接宾语,与tell sb.that ...类似.是的,that从句是宾语从句.
8.I get enough room to seat.这里的不定式是做定语还是状语?为什么?
答:seat是及物动词,应该为sit.这个与have sth.to do不同,我认为是状语.
9.When taken according to the directions,the medicine has no side effect.
我不明白这里的taken.句子里面不是已经有when可以引导从句吗?为什么还要用非谓语?
答：when the medicine is taken .,the medicine has .
-->When it is taken .,the medicine has .
-->状语从句中的省略（主语+BE)
条件1：状语从句中的主语与主句的主语相同,这里的it=the medicine
条件2：从句的谓语动词中有be (助动词或系动词都行）
如果从句的主语为it (与主句主语不是同一物时,也可以省略）如：If (it is ) possible,I will do sth.
When (it is necessary),we'll do sth.