Chia các động từ sau :
   1. If today ............... (to be/not) cold, we would go swimming. 
   2. If  I throw an object away, it ........... (drop).
   3. If Hoang ............... (to be) to study harder, he would get good marks.
   4. If Kim  ..................... (to be/not) lazy, she wouldn't have failed her exam.
   5. If they  ................. (go/not) to her birthday party tomorrow, they would be very angry.
   6. If Lin (know) ................ his father's telephone number, I would give it to you.
   7. If I learnt English harder, I .................. (pass) the test yesterday.
   8. If Nam .............. (see) her, he would have said 'hello'. 
   9. If my sister .............. (miss) the bus, she would have been late for her interview.
   10. If it don't rain, I and my best friends ............. (go) out.