人行横道的信号灯变绿了。

The crosswalk ___signal changes to green.

她举起手示意要发言。

She raised her hand to ___signal that she wanted to speak.

老师举起手作为信号让学生们安静下来。

The teacher raised her hand as a ___signal for the students to quiet down.

老师举起手示意学生们安静。

The teacher raised her hand to ___signal the students to be quiet.

电梯里没有信号，我打不通电话。

There's no ___signal in the elevator, so I can't make a call.