It is generally believed that teaching is ___________it is a science.
Because he works far away from his parents, he visits them only_____.
It is known that a football team _____ 11 members .
If students have free ____ to the public library, they will be likely to do more reading.
—How about going for a picnic this weekend?— Why not? _________.
In the old days, people ______ a fire with wood in our village.