绿菜花育苗时,当幼苗()真叶时分苗。
A.1~2
B.3~4
C.5~6
D.6~7
参考答案:A
The city has changed little in the last years.
A.little
B.a little
C.few
D.a few
电空位操纵空气制动阀在制动位时,空气制动阀将直接向()充风
A、工作风缸
B、制动缸
C、容积室
D、制动管