S-5：sell someone down the river 出卖某人（在紧要关头）
A:It seems that you are getting with Jack like a house on fire.
A:看来你跟杰克关系不错，挺热乎的。
B:Yeah. We really hit it off.
B:是的，我俩特别合得来。
A:Well, you'd better keep him at arm's length, or he will take advantage of you and sell you down the river.
A:哦，你最好避免与他过分亲近，否则他会利用你，在紧要关头出卖你。
B:Why? What kind of person do you take him for, anyway?
B：为什么？你把他看成什么人了？
A:Well, go and ask Mary. She'll tell you.
A:你去问玛丽吧，她会告诉你的。
