1. Walking home is not a good idea.

-> If I were you, I wouldn't walking home.

2. Throw a stone into water and it sinks.

-> If you throw a stone into water, it sinks.

3. Don’t take this job if you don’t really want it.

-> Unless you really want the job, don't take it

4. Be faster. Otherwise, they will catch you.

-> If you aren't faster, they will catch you.

5. Work hard, or you will fail the exam.

-> You must work hard if you don't want to fail the exam.

$_Study well_$

1. Walking home is not a good idea.

  → If I were you, I wouldn't walk home.

2. Throw a stone into water and it sinks.

  → If you throw a stone into the water, it sinks.

3. Don’t take this job if you don’t really want it.

  → Unless you really want this job, don't take it.

4. Be faster. Otherwise, they will catch you.

  → If you are not fast, they will catch you.

5. Work hard, or you will fail the exam.

  → You must work hard in order not to fail the exam.