The ship radioed a call for help.

那艘船用无线电发出求救信号。

The ship radioed for help.

这艘船发出无线电求救信号。

Suddenly a steamer hove in sight. The captain immediately gave an order to send out a signal for rescue.

"突然一艘轮船驶入视线,船立刻命令发出求救的信号。"

The submarine signaled for help.

潜水艇发出求救的信号。