17世纪中叶A.V.Leeuwenhoek用自制显微镜观察到了()
A.植物细胞的细胞壁
B.精子、细菌等活细胞
C.细胞核
D.高尔基复合体等细胞器
E.细胞的有丝分裂
参考答案:B
-How many books are there in the box?
-_______.
A. None B. No one C. No
He won the first place in the boys' l00-meter race. His father is_______of him. [ ]
A. happy
B. pleasure
C. pride
D. proud