His writing is so confusing that it's difficult to make out ________ he is trying to express.

6. --- I don’t know ______ I can improve my English. --- You can read some English books and magazines.

Choosing the right dictionary depends on ______ you want to use it for. 

---Peter is not himself these days.---well, could you tell me________?

Jack asked John ______ when he met him in the street.