问题
单项选择题
2，1，5，7，17，( )
A．26
B．31
C．32
D．37
答案
参考答案：B
解析：
本题的规律是：2＝21+1，1＝21-1，5＝22+1，7＝24-1，17＝24+1， (31)＝25-1。
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2，1，5，7，17，( )
A．26
B．31
C．32
D．37
参考答案：B
解析：
本题的规律是：2＝21+1，1＝21-1，5＝22+1，7＝24-1，17＝24+1， (31)＝25-1。
| 阅读理解。 | |
| |
| 1. The writer of this letter is ______. | |
| A. a student B. a teacher C. an officer D. a driver | |
| 2. ______ is one of the reasons why the forests are disappearing. | |
| A. Rain B. Tourism C. Planting D. Breathing | |
| 3. The writer advises Mr Heppell to ______. | |
| A. stop shops from using paper any more B. use paper which is made from tress C. stop shops selling paper made from trees D. plant more and more trees in the future | |
| 4. How can Mr Heppell contact the writer? | |
| A. By calling her B. By interviewing her C. By visiting her D. By e-mailing her | |
| 5. What's the purpose of this letter? | |
| A. To know more about Mr Heppell B. To make friends with Mr Heppell C. To ask Mr Heppell to teach in the school D. To ask Mr Heppell to help protect forests |