17000 bài tập tách từ đề thi thử môn Tiếng Anh có đáp án (Phần 3)

We called an ambulance as soon as we realised that he seemed to be having

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We called an ambulance as soon as we realised that he seemed to be having ____ heart attack.

a

an

the

no article

Giải thích

Đáp án A