B-2：back up 支持
A: I decide not to buy the mobile phone.
A: 我决定先不买手机了。
B: But you told me yesterday you would.
B: 可昨天你还说你会买。
A: I have changed my mind.
A: 我改主意了。
B: What's wrong?
B：怎么了？
A: My family doesn't back me up at this point. They think it is useless to me now as a student.
A: 我们家人不支持我。他们说我现在还是学生，手机对我没用。
