1) They work efficiently.
=> They are efficiently worker
2) Tom is a good speaker of English.
=> Tom speaks E. well
3) Throwing rubbish pollutes the environment.
=> The environment'll be polluted if throw rubbish
4) Work harder and you will succeed in the exam.
=> If you work harder, you'll succeed in the exam
5) Be careful or you will fail the exam
=> If you don't carefull, you'll fail the exam