He only thought about having a holiday abroad after he retired. => Only
He only thought about having a holiday abroad after he retired.
=> Only _________________________________________________.
Đáp án: Only after he retired did he think about having a holiday abroad.
Giải thích: Cấu trúc: Only after + N/Ving/Clause + trợ động từ + S + Vinf: chỉ sau khi
Dịch: Chỉ sau khi nghỉ hưu ông mới nghĩ đến việc đi nghỉ ở nước ngoài.