Good grammar websites:

• Perfect English Grammar

• Englisch Hilfen

• Study Zone

• Agenda Web

Passive

• The passive in your language

Verbs - Tenses

• Present Simple OR Present Continuous?

• Present Perfect Continuous

Verbs - Other

• State Verbs

• Questions

• Conditionals

• Reported speech

Adverbs:

• very, too, enough, so and such

Prepositions:

• Read about Prepositions

• Prepositions exercises

• Prepositions exercises

Pronouns:

• Pronouns 1

• Pronouns 2

• Pronouns 3

Determiners:

• Another / Other

• Articles explained in your language