1.happen to 碰巧；发生；偶然

Do not wait for good things to happen to you. You need to walk towards happiness.
不要等待好事降临，你要向幸福进发。

If you happen to talk to him, have him call me.
如果你碰巧能和他说话，让他给我打个电话。

2.listen to 倾听；聆听；收听

Listen to criticism but don't be crushed by it.
听取批评意见，但不要被它击垮。

A patient will usually listen to the doctor'sadvice and act on it.
患者通常都会遵照医嘱行事。