【单选题】We are told everywhere. It's our duty to keep our school clean and tidy. [ ]
A.
not to make much noise
【单选题】关于分子与器壁的碰撞频率,下面说法正确的是?
【单选题】Trees and flowers _____ every year to make our school more beautiful. A. plant B. are planted C. were planted
【单选题】In class, Miss Zhang is really __ about our study. But after class, she always tries many ways to make our school life not so boring.
【单选题】下列哪个选项是表达式(8/5)的计算结果?
【单选题】_______ has been done to make our school more beautiful.
【单选题】下列哪个选项是表达式(2+'A')的运算结果?
【单选题】To make our school beautiful, we _____ throw rubbish here and there.
【多选题】关于直流电动机,下列叙述正确的是 [ ]
C.
直流电动机的换向器是由两个彼此绝缘的铜制半环组成的
D.
电源的正负极和磁场的方向同时改变,直流电动机的转动方向也改变