Ответ:

1. If you wear sandals in the mountains, you'll slip on the rocks.

2. If Rita forgets her homework, the teacher will give her a low mark.

3. If they go to the disco, they will listen to loud music.

4. If you wait a minute, I'll ask my parents.

5. If you send this letter now, she'll recieve it tomorrow.

6. If I do this test, I'll improve my English.

Объяснение:

В части предложения с условием if используем Present Simple, во второй - will+Infinitive