He learned English for three years. Then he moved to London.

40/40

After he had moved to London, he learned English for three years

By the time he moved to London, he had learned English for three years

After he moved to London, he had learned English for three years

By the time he had moved to London, he learned English for three years

Giải thích

Đáp án đúng: B

Giải thích: By the time: vào lúc

Dịch: Anh ấy đã học tiếng Anh trong ba năm. Sau đó, anh chuyển đến London.

= Vào thời điểm anh ấy chuyển đến London, anh ấy đã học tiếng Anh được ba năm.