Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the following questions ___________, Joe was annoyed to find that he had left his key at the coff

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Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the following questions

___________, Joe was annoyed to find that he had left his key at the coffee shop

After returned to his office

To have just returned to his office

Upon returning to his office

Having been returned to his office

Giải thích

Đáp án C

upon + Ving: vào lúc, đúng lúc