Whose ping pong bat is this? — I’m not sure. I think it ______be Tom’s.

I wonder ______ you’ll water this kind of tree. ——- Once a week.

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

I ________ clean my room on weekdays. I have no time.

I thinknecessary to do some running in the morning.