题目内容
Sam ________ coins since he was eleven years old, and now he has hundreds of them.A. collected
B. had collected
C. has been collecting
答案：C
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提示：
| “since”以前某时到现在一直……，用现在完成进行时
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Sam ______ coins since he was eleven years old, and now he has hundreds of them.
| A．collected | B．had collected |
| C．has been collecting | D．had been collecting |