防止锅炉爆炸的措施（）等。
A、防止超压
B、防止过热
C、防止腐蚀
D、防止安全阀故障
参考答案：A, B, C, D
-- Did you watch the basketball match last weekend?
--- Yes, I did. It was covered , and I think it was wonderful.
A．lively
B．alive
C．living
D．live
两根平行导体中通过方向相反的电流时，则这两导体将受到（）的力。
A.相互排斥
B.相互吸引
C.方向不定
D.为零
