| Dr Ma operated _______ over 150 patients _______ his visit to that poor town . |
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[ ] |
| A. in, while B. on, during C. for, in D. on, for |
| Dr Ma operated _______ over 150 patients _______ his visit to that poor town . |
|
[ ] |
| A. in, while B. on, during C. for, in D. on, for |