5 French Phrases – Find the missing words

I didn't know what to do here
Je ne savais _____ faire ici

Do you want to finish your toast?
Vous voulez finir _____ tartine ?

I think it is false
Je pense _____ c'est faux

I would like to teach you something
Je voudrais vous _____ quelque chose

I never thought about it
Je n'_____ ai jamais pensé