Work on the following exercises:

Relative clauses: Decide which relative pronoun must be used. There can be more than one right answer. 

Find the right word: Give the translation of the words in the last. Regard the spelling of the words!

Contact clause? : Say, if you can leave out the relative pronoun and build a contact clause or not. 

Tenses: Give the right tenses in the gaps. If you only need one word, mark the empty one with a -.