题目内容
【题目】Look! Mary____ doing ____homework.
A. is; one's B. is; her C. are; his
【答案】B
【解析】现在进行时态构成be doing.

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题目内容
【题目】Look! Mary____ doing ____homework.
A. is; one's B. is; her C. are; his
【答案】B
【解析】现在进行时态构成be doing.