Bộ 5 đề thi giữa kì 1 Tiếng Anh 12 Global Success có đáp án - Đề 4

Mark the letter A, B, C or D on your answer sheet to indicate the underlined part that needs correct...

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Alexander Fleming was working in his lab when he was discovering penicillin by accident.

was working

when

was discovering

by

Giải thích

Choose C