There are two_________ books in the library.
The robot needs _______ once a month. And we will check it for you for free.
We didn’t know how to find them because they didn’t tell us _______.
In order _______ his English,he joined an English club.
Don’t make the students _______ this or that . They are busy.
---It’s said that scientists are working hard to ________ a way to deal with H7N9 avian influenza(H7N9禽流感)---Really? That’s great!