两条刮板链的伸长量达到或超过原始长度的2.5%时，则需要更换，更换时要成对更换。
参考答案：对
—My sports shoes are _______ out.
—How long have you _______ them? [ ]
A. worn; bought
B. wearing; had
C. wearing; bought
D. worn; had
下面关于C++语言的描述错误的是
A．C++语言支持数据封装
B．C++语言中引入友元没有破坏封装性
C．C++语言允许函数名和运算符重载
D．C++语言支持动态联编
