1. I would like (explain, to explain) you everything. 2. Do you want (buy, to buy) this house? 3. Can you (to play, play) chess? 4. Sorry, it's time for me (leave, to leave). 5. People must (to help, help) each other. 6. I had (stay, to stay) in the office till 8 p.m. yesterday. 7. Drivers should (to be, be) very attentive. 8. May I (to come, come) in? 9. We wish him (achieve, to achieve) his aim. 10. You could (to do, do) it yesterday. 11. We will have (answer, to answer) this letter. 12. I'm very glad (to see, see) you again. 13. If you have a high temperature, you should (to stay, stay) in bed. 14. I could (to give, give) you a piece of advice. 15. Are you going (take part, to take part) in this ​