(Viên chức Mầm non) bài tập tiếng Anh theo chủ đề có đáp án - Test 2

I would have saved myself a lot of time and trouble over the years _____ then what I know today.

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B. Choose the word or phrase - a, b, c or d - that best completes the sentences.

I would have saved myself a lot of time and trouble over the years _____ then what I know today.

if I knew

only had I known

I had known

had I known

Giải thích

Đáp án đúng là d