英语继续提问!27.I didn’t make her out at first because I _C_×_B__

英语继续提问!
27.I didn’t make her out at first because I _C_×_B__ my glasses.
A.has not worn
B.was not wearing
C.did not wear
D.had not worn
为什么选B,请说明理由
28.By the time the girl was nine years old,she _A_×_C__ books for grown-ups.
A.had already read
B.already read
C.was already reading
D.would already read
为什么选C,请说明理由
29.They asked me to have a drink with them.I said that it was at least ten years since I ___C ×A__ a good drink.
A.had enjoyed
B.was enjoying
C.enjoyed
D.had been enjoying
为什么选A,请说明理由