Some Topics covered in the TOEFL test especially for Grammar part are as follows.
1. Elliptical Construction
2. Subjunctive and Preference
3. Modal
4. Tenses
5. Causative
6. Gerund and Infinitive
7. Active Participle
8. Concord
9. Passive Voice
10. Word Order
11. Dependent and Independent clause
12. Derivative
13. Conditional Sentence
14. Pronouns
15. Conjunction
William Gregory (The Real TOEFL)