在一定条件下，可发生反应：RO3n-+F2+2OH-==RO4-+2F-+H2O

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问题选择题

在一定条件下，可发生反应：RO₃^n-+F₂+2OH^-==RO₄^-+2F^-+H₂O。则RO₃^n-中R元素的化合价是

A．+4

B．+5

C．+6

D．+7

答案

答案：B

填空题

用括号内所给单词的适当形式填空。

1. Sally's school orchestra is _____ (play) it.

2. What about _____ (listen) to the concert?

3. Mr. Wang is our English teacher, so he likes _____ (west) classical music.

4. His sister _____ (go) to America, hasn't she?

5. How many _____ (composer) are there in the hall?

单项选择题

冷藏货物运输时，如冷藏舱内有异味可用（）去味。

A．粗茶

B．臭氧

C．洒醋酸水

D．A、B、C均可