Sure, here are the sentences with the correct verb forms:

17. My students rarely **rain** a word in English! (This sentence seems incorrect as "rain" is not a suitable verb here. Perhaps you meant "My students rarely **say** a word in English!")

18. It rarely **rains** in summer.

19. Look! It **is raining** cats and dogs! We can't go out now.

20. I never **get up** before 7.30.

21. Are you sure this dress **suits** me?

22. Susan usually **does** her homework in her bedroom.

23. The Earth **goes** around the sun.