Bộ 10 đề ôn thi học sinh giỏi Tiếng anh 9 năm 2023 có đáp án (Đề 5)

Scientists have tried very hard to find a cure for AIDS.

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Scientists have tried very hard to find a cure for AIDS.

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Giải thích

Enormous efforts/attempts have been made by scientists to find a cure for AIDS.