listen for 表示注意倾听,for 有等待,期待的意思
例句与用法:
1.She shouted on the mountaintop and listened for the echo.
她在山顶上大声喊着,然后聆听着回声.
2.For over two hours,her arrival had been listened for.
足足有两个多小时,人们一直等待着听她到来的声响.
listen in on:偷听,窃听
listen in 偷听,窃听
How dare you two listen in on my telephone conversation!
你们两个竟敢偷听我打电话!
It's rude to listen in on other people's telephone calls.
偷听别人的电话是不礼貌.