远期外汇交易是由于（）而产生的。
A.金融交易者的投机
B.为了避免外汇风险
C.与即期交易有所差别
D.银行的业务需要
参考答案：B
—What has made him look like lacking sleep?
—_______ his wife is ill and he has to get up several times a night to attend to her.
A．For
B．Because
C．That
D．What
The computer system ______ suddenly while he was searching for information on the Internet. [ ]
A. broke down
B. broke out
C. broke up
D. broke in
