在脚轮车上必须配备那些安全设施？

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问题问答题简答题

在脚轮车上必须配备那些安全设施？

答案

参考答案：

必须有灭火器、有瓦斯报警仪、有防止车辆倒滑的大木屑、车上要安装反光贴等易发现的标致。

选择题

I had wanted to help you last night but I couldn't spare any time, for I ______ a composition which

I have to hand in this morning. [ ]

A. wrote

B. was writing

C. had written

D. have written

填空题

科研中假设的作用包括：指导研究、逻辑推导、（）。