The _________ of the building was so strong that it didn’t fall down in the terrible earthquake.
How many ______ medicine are used for the children of six years old?
Eating fruit and vegetables can help you ______ more vitamins.
Here ______ in the classroom.
We should keep our classroom ______.
—English is difficult for me. I can’t learn it well. —Don’t give up. Nothing is difficult if you work hard.