关于钢塑复合管及铝塑复合管的特点，叙述正确的有（）。
A.耐压强度高
B.可曲挠
C.水流阻力小
D.耐腐蚀
E.耐热性能好
参考答案：A, B, C, E
The computer was invented in the 1940’s and ______ quite a lot ever since.
A．was changed
B．had changed
C．has been changed
D．will change
酸雨是指pH值（）的大气降水。
A.＞5.6
B.＞7
C.＜5.6
D.＜7
