机动车经（）部门登记后，方可上道路行驶。
A、道路运输管理机构
B、公安机关交通管理
C、工商部门
D、税务部门
参考答案：B
— Bob! How is your project? I heard you started it last Friday, right?
— Oh! I_____ for it. But I haven't decided when to do it. [ ]
A. have prepared
B. had prepared
C. have been preparing
D. was preparing
如图所示，集气瓶内充满某混合气体，置于光亮处，将滴管内的水挤入集气瓶后，烧杯中的水会进入集气瓶，集气瓶内的气体是( )
①H2、O2②Cl2、CH4③NO2、O2④N2、H2
A．①②③
B．②④
C．③④
D．②③
