Don't just look on when an accident happened.
事故发生了不要仅仅旁观。
Investors can only look on, baffled.
而投资者只能困惑地进行旁观。
he had a worried look on her face.
她一脸担忧的样子。
I could tell by the look on her face that something terrible had happened.
从她的脸色我可以看出，发生了可怕的事情。
There was an amused look on the President's face.
总统面带愉悦的神情。