e.g. If you get a pet, you won't be (not be) lonely. 21 If you go online, you (find) more information on the subject. 22 You'll prepare for the test more easily if you (keep) notes of the lectures. 23 If you (not switch off) your PC, it can break down. 24 If you look after your little sister, your parents (not have to) worry about her. 25 If you (not sleep), you get tired. 26 Whenever he (use) a new gadget, he follows the instructions. 27 If you (write) an essay, I'll help you to check it. 28 My friends and I (go) to the zoo if it's sunny. 29 When you (work) hard, you get good results. 30 If I get her email address, I (send) her my invitation via email.

Ответ: смотри решение ниже

1. 21 If you go online, you will find more information on the subject. (will find - Future Simple)
2. 22 You'll prepare for the test more easily if you keep notes of the lectures. (keep - Present Simple)
3. 23 If you don't switch off your PC, it can break down. (don't switch off - Present Simple)
4. 24 If you look after your little sister, your parents don't have to worry about her. (don't have to - Present Simple)
5. 25 If you don't sleep, you get tired. (don't sleep - Present Simple)
6. 26 Whenever he uses a new gadget, he follows the instructions. (uses - Present Simple)
7. 27 If you write an essay, I'll help you to check it. (write - Present Simple)
8. 28 My friends and I will go to the zoo if it's sunny. (will go - Future Simple)
9. 29 When you work hard, you get good results. (work - Present Simple)
10. 30 If I get her email address, I will send her my invitation via email. (will send - Future Simple)

Ответ: смотри решение выше