固位作用好、但支持和稳定作用差的卡环臂是（）
A.1型卡臂
B.2型卡臂
C.3型卡臂
D.4型卡臂
E.5型卡臂
参考答案：B
We often play basketball with __________ at the weekends.[ ]
A. other schools
B. others school
C. other school
D. others schools
下图是某细胞进行有丝分裂的简图，据图回答
A图中染色体数目为（）
