1.Unless you obey the rules, otherwise you will be punished.
You must obey the rules, otherwise you will be punished.
You must follow the rules, otherwise you will be punished.
Unless you obey the rules, you will face the consequences.
2.A fish dies if you don't keep it in the water.
A fish can't survive if you take it out of the water.
A fish can't survive without water.
A fish will die quickly without water.
3.No body can learn English well, if he doesn't work hard on it.
No one can learn English well, if he doesn't work hard on it.
You can't learn English well, if you don't work hard on it.
You can only learn English well if you work hard on it.
4. Unless you start right now you will be late for the meeting.
You must hurry up, or you will be late for the meeting.
Hurry up, or you will be late for the meeting.
Unless you start right now, you will miss the meeting.