激光束照到光盘的坑槽处时反射回的光（）。
A.很弱
B.较强
C.很强
D.中等
参考答案：A
128. If you want to speak English fluently, you should first practise _____ English _____.
A．everyday; everyday
B．every day; everyday
C．everyday; every day
D．everyday; everyday
计算3x+x的结果是[ ]
A.3x2
B.2x
C.4x
D.4x2
