A:C2H4
B:C3H6
C:C4H8
D:C4H10
正常男子体细胞中的染色体只有XY,其中的Y既可以传给其女儿,又可以传给其儿子。
如图所示,小物体A与圆盘保持静止,跟着圆盘一起做匀速圆周运动,则A物体的受力情况是( )
— My cousin is good at all his subjects at school, but he never ________.
— What a ________ boy! We should learn from him.