Употребите глаголы в скобках во времена группы Simple либо Continuous. 1.

1. I think of selling my car. Would you be interested in buying it? 2. I think you should sell your car. You do not use it very often. 3. What are you doing? Be quiet! I am thinking. 4. We can go out now. It is not raining any more. 5. Do you still smoke? No, I gave it up. I do not smoke for any more.

Present Simple is used for common actions. Present Simple is formed with the help of the suffix - s or - es. We add this suffix to verb in the third person singular. 

Present Continuous is used for action tat takes place at the moment of speech. Present Continuous is formed with the help of the auxiliary  verb to be and with the help of the suffix - ing.