单项选择 There are so many books----- that I don not know which

D to choose from
这是状语从句(从句主语与逻辑主语一致),在此句中,从句主语是I,所以主句的逻辑主语也为I,故要用to choose,即choose这个动作是I发出的,不存在被动.
但是to choose 不定式做定语修饰books就必须加from,因为to choose 为不及物动词词组,books在to choose from这个从句中做宾语,构成介宾关系,from也就限定了choose的范围.