Teenagers should learn to protect ______ from all kinds of danger.
Do you know the teacher who is having an English lesson.
Let’s buy some more books this afternoon.
—Would you please pass me the sugar?— ____. Here you are.
In our school library there ____ a number of books on science and the number of them ____ growing larger and larger.
It’s said that Armstrong sent a message to Mission Control _____ said that two huge, strange objects landed near them and were watching them.