电动车是用来牵引焦罐车，以下选项中不属于焦罐车构造的是( )。
A．焦罐 B．焦罐电车 C．运载车 D．交换器
参考答案：D
- Did you see a man in black pass by just now?
- No, sir. I _______ a newspaper.[ ]
A. read
B. was reading
C. would read
D. was reading
蝗虫对农作物造成的危害很大。当蝗灾发生时，人们进行灭蝗的最佳时机应是[ ]
A．受精卵
B．若虫
C．蛹
D．成虫
