---How often does the boy play sports?---A. Once a weekB. Four hoursC. In an hourD. At 7pm

---How often does the boy play sports?
---
A. Once a week
B. Four hours
C. In an hour
D. At 7pm

(答案→)A. Once a weekB. Four hoursC. In an hourD. At 7pm解析：本题问的是频率，once a week 意思为每周一次，表示的是频率，故本题选A。

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