英文文法請益~ 4/5 - 考試

請教高手大大幾題文法問題~
出處:倪明高普講義
1.甲:I like you hat.
乙:But it's only the same hat------you wear now.
(A)that (B)as
答案:(B),題目不是有"only",僅剩一頂帽子(同一頂)，所以應該選(A)?

EX: That is the same book as I lost (共2本書)
.......................that.......(共1本書)

2.I cannot perceive------the difference lies.
(A)where (B)what
答案:(A),為何不可選(B),空格前無先行詞阿!


3.As you sow,------shall you reap.
(A)which (B)so (C)what
答案:(B),不明白為何選它


4.Can you tell me-----?
(A)who is he (B)whom he is (C)who he is
答案:(C),為何(B)不行? 有時覺得關係代名詞與間接問句會讓我混淆@@"

5.You are too young to have the right ,------you?
(A)aren't (B)are
答案:(A),too.....to不是有含否定意思,所以附加問句為肯定,應該選(B)?

感謝大大的解惑~~

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