Put the verbs in brackets into the correct tense to form conditionals. 1. We'll miss the clean-up day if we (not leave) now.
2. I (help) you if you'd asked me to.
3. I would work at the animal shelter if I (have) more free time.
4. We (not/solve) the problem of illiteracy unless everyone has access to free education.
5. If I had saved more money, I (go)on the trip to Africa.
6. If I lived closer to town, I (volunteer) at the homeless shelter.
7. They will close the library if we (not/start) a campaign to stop them.
8. Unless the countries make peace with each other, this war (never/end)

prezent simple - простая форма глагола настоящего времени.
состоит из начальной формы глагола, употребленной без предлога to. указывает на действие, периодически повторяющееся. обычно употребляется с наречиями типа usually (обычно), often (часто), словосочетанием every day и так далее.
например: I go to school every day. - я хожу в школу каждый день. 

форма глагола present continios указывает на длительность действия или действие, которым субъект занят в данный момент. состоит из вс глагола-связки to be, употребляемого в настоящем времени (am, are, is - в зависимости от лица и числа глагола) и основного глагола с окончанием -ing. обычно эта форма сопровождается словосочетаниями типа whole day (целый день), at this moment (в этот момент), now (сейчас).
например: Today he is reading a book whole day. (Сегодня он целый день читает книгу.)

1. My little sister goes to school every day. 2. I have seen you the other day coming out of the library with a stack of books. 3. I traveled by car this summer. 4. It often snows in winter. 5. Some students have done lessons by fits and starts. 6. Wait a little, I shall phone for a taxi. 7. The building of the trade centre began a month ago. 8. Attendance is very important. 9. Ann will practice the piano all the morning tomorrow. 10. Charles wakes up at seven and has breakfast at half past seven. 11. Mother always cooks in the morning. 12. I will take my last exam next Monday. 13. English is an international language. 14. We shall play chess in half an hour. 15. It was bitterly cold yesterday. 16. My friend goes there nearly every week. 17. Yesterday my friend bought a new car. 18. The postman has brought the morning mail only at 10 o‘clock/