京九线光缆是20芯的，那么它属（）结构形式
A.层绞式光缆
B.单位式光缆
C.骨架式光缆
参考答案：B
It is the third time that she has won the race, ______ has surprised us all.
A．that
B．where
C． which
D． what
遗传方式是
A．常染色体显性遗传
B．X性连锁显性遗传
C．多基因遗传
D．常染色体隐性遗传
E．X连锁隐性遗传
