Make the question for the underlined words.
Researchers started to search for evidence of aliens many years ago.
How did researchers start to search for evidence of aliens?What did researchers start to search for many years ago?Where did researchers start to search for evidence of aliens?When did researchers start to search for evidence of aliens?Hướng dẫn giải:Dạng câu hỏi cho cụm từ “many years ago” → ta cần dùng trạng từ hỏi chỉ thời gian “When”.
Cấu trúc: When did + S + V (nguyên thể)...?
