There are millions of websites on the Internet and there _________ a lot of useful ________ on the websites. 

In autumn, many green ________ change to yellow, orange or red. 

If you have a toothache, you should see a            .

－What are these?－They are_________.

 —Excuse me, is this ________ new pencil sharpener?  —Yes, it’s ________. He bought it just now.