1. He has been an English teacher for 20 years
→ Phủ định: He hasn't been an English teacher for 20 years
→ Câu hỏi: Has he been an English teacher for 20 years ?
2.We are having an English test next Monday
→ Phủ định: We aren't having an English test next Monday
→ Câu hỏi: Are you having an English test next Monday?
3.The people were priendly
→ Phủ định: The people weren't friendly
→ Câu hỏi: Were the people friendly?