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职称英语
综合类C级
[单选题]
Sulphur has [occasionally] been found in theearth in an almost pure state.
A.regularly
B.accidentally
C.sometimes
D.successfully
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![Sulphur has [occasionally] been found in theearth in an almost pure state.](https://img.zhaotiba.com/tiku75/15022169.jpg "Sulphur has [occasionally] been found in theearth in an almost pure state.")