1.He lost his umbrella yesterday.
→ He didn't lost his umbrella yesterday.
2.I am doing my homework now.
→ I am not doing my homework now.
3.They left the door open last night.
→ They didn't leave the door open last night.
4.We were eating dinner at this time yesterday.
→We were not eating dinner at this time yesterday.
5.She will buy a new english dictionary the next day.
→ She will not buy a new english dictionary the next day.
6.The children went to school by bus.
→ The children didn't go to school by bus.
7.Ann's brother is going history at university.
→ Ann's brother is not going history at university.
8.Mr.Nam will visit his grandparents tomorrow.
→ Mr.Nam will not visit his grandparents tomorrow.
9.They usually play football at this stadium.
→ They don't usually play football at this stadium.
10.My father was working in a bank.
→ My father wasn't working in a bank.
11.Tom's mother often helps him with the homework.
→ Tom's mother doesn't often help him with the homework.
12.Angela did her homework very quickly yesterday.
→ Angela didn't do her homework very quickly yesterday.
- Answered by Meett1605