-- _____is that used for?---_____ the floor.
Dr Yuan Longping grows _____ is called super hybrid rice, _____ has a high output.
---Do you want to come with us?---No, I would rather ______ at home than _____ with you.
Only when it is hungry ______ a human being.
My teacher as well as my classmates _____ very kind to me.
The house rent is expensive. I’ve got about half the space I had at home but I have to pay _____ here.