Comparative and superlative

Here you can find some information with exercises on comparative and superlative. Here is the key to the exercises.

What and which

Here you can find a document with information on the use of 'what' and 'which'.

Object and subject questions

Here you can find some information with exercises on subject vs. object questions.  Here you can have access to the key for the exercises. Here you can have access to a webpage with more exercises on the topic.