如果用弹簧来平衡各绳或链的张力，则弹簧应在（）状态下工作。
A、伸长
B、压缩
C、即不伸长也不压缩
参考答案：B
_____ he didn't know the custom in that country; otherwise, he wouldn't have made such a mistake. [ ]
A. Approximately
B. Accidentally
C. Obviously
D. Occasionally
He has donated some money to those who________ in poverty, which of great help.
A．live, is
B．lives, are
C．live, are
D．lives, is
