1. [单选题]在高等植物体的( )中，叶绿体数目最多。
A. 表皮细胞
B. 茎尖细胞
C. 皮层细胞
D. 叶肉细胞
2. [单选题]A great number of _______students said they were forced to practise the piano.
A. to question
B. to be questioned
C. questioned
D. questioning
3. [单选题]56_______
A. However
B. Moreover
C. Instead
D. Therefore
