thì HTĐ
→ ( + ) S + vs/es → he often goes to school by bus
→ ( - ) S + don't /doesn't + V nguyên mẫu → she doesn't go to school by bus / i don't go to school by bus
→ (? ) do / does + S + V nguyên mẫu → do they often play football ? / does he always get good mark ?
thì HTTD
→ ( + ) S + be + V-ing → I am having breakfast now
→ ( - ) S + be not + V-ing : he isn't eating bread now
→ ( ? ) be + S + V-ing : is she playing the piano now ?