30. Work hard or you can't pass the exam.

⇒ If you don't work hard, you can't pass the exam.

31. Practice speaking every day or you can't improve your pronunciation.

⇒ If you don't practice speaking every day, you can't prove your pronunciation.

32. Unless we reduce the use of water, we'll have to pay more money.

⇒ If we don't reduce the use of water, we'll have to pay more money.

33. If she doesn't put the coat on, she will be cold.

⇒ Unless she puts on her coat, she will be cold.

34. If he proves his spelling, he will get good grade.

⇒ Unless he proves his spelling, he won't get good grade.

35. Leave me alone or I will call the police.

⇒ If you don't leave me alone, I will call the police.

36. I won't come if they don't invite me.

⇒ Unless they invite me, I won't come.

37. You arrive at the office earlier than I do, please turn on the air-conditioner.

⇒ If you arrive at the office earlier than I do, please turn on the air-conditioner.

38. Don't tell lies to your boss or you'll be fined at once.

⇒ If you tell lies to your boss, you'll be fined at once.

39. You must tell me the whole truth or I won't help you.

⇒ Unless you tell me the whole truth, I won't help you.

40. Stop talking or I'll punish you.

⇒ If you talk, I'll punish you.

Chúc bạn học tốt!

@meowuwu856

Cho mình xin 5 sao và 1 tim cám ơn nha =)