无论哪种管道工程，都必须具备的质量要求是（）。
A.不泄漏
B.稳定耐久
C.一定的抗震性能
D.具有互换性
参考答案：A, B, C
某国有企业6月1日收到银行的委托收款通知，如该企业对收款人委托收取的款项需要拒绝付款的，应当在（）日内出具拒绝证明。
A、1
B、3
C、5
D、7
Which of the following statements is true about his friend
A．Writing exhausts his friend.
B．His friend collects a lot of things to write.
C．His friend always has enough material to write on.
D．His friend is doing research to write a paper.
