题目内容
Can children swim in this pool?
--Yes. However, at no time _____ they do so alone.
A. may B. need C. could D. should
D
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Directions: Read the following text and choose the most suitable heading from A-F for each paragraph.There is one extra heading which you do not need.
| A.Causes of overusing fluoride | B.Negative effects of fluoride |
| C.Safe use of fluoride | D.The expert’s background information |
| E.No need to worry about fluoride poisoning | |
| F.Solutions to improper use of fluoride | |
| 【小题1】 | |
| 【小题2】 | |
| 【小题3】 | |
| 【小题4】 | |
| 【小题5】 | |