Don't just look on when an accident happened.

　　事故發生了不要僅僅旁觀。

　　Investors can only look on, baffled.

　　而投資者只能困惑地進行旁觀。

　　he had a worried look on her face.

　　她一臉擔憂的樣子。

　　I could tell by the look on her face that something terrible had happened.

　　從她的臉色我可以看出，發生了可怕的事情。

　　There was an amused look on the President's face.

　　總統面帶愉悅的神情。