单项选择题
Whatever you do, you ______ click with the right mouse button or the program will crash.
单项选择题 It is necessary that anyone ______ exercises every day if he wishes to keep healthy.
单项选择题 I cannot sleep. The dog next door is making too much noise. I wish it ______ quiet.
单项选择题 He has never seen the Greens and he knows ______ about them.
