15000 bài tập tách từ đề thi thử môn Tiếng Anh có đáp án (Phần 53)

She could ______ in the garden when we came around, which would explain why she didn’t hear the bell. A. work B. be working C. have worked D. have been working

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She could ______ in the garden when we came around, which would explain why she didn’t hear the bell.

work

be working

have worked

have been working

Giải thích

Đáp án D