四大家鱼精子入水后限为（）之内受精。
A.1h
B.5h
C.30～45s
D.70～80s
参考答案：C
下图为一个简单的互联网示意图。其中，路由器S的路由表中到达网络10.0.0.0的下一跳步IP地址为( )。 [*]
They managed to ______their experiments in spite of the difficulties.
[ ]
A. carry on
B. carry off
C. carry out
D. carry in
