预混合型原子化器一般由（）组成。
A.雾化器
B.预混合室
C.燃烧器
D.石墨管
参考答案：A, B, C
_____, he makes little progress. So he is trying new methods of study. Which of the following is WRONG? [ ]
A. Hard as he works
B. Hard although he works
C. Hard though he works
D. Although he works hard
大比例尺成图一般采用（）分幅。
A、矩形
B、梯形
C、方格网
D、带状
