--How about your English?--I found ________ hard to learn it well.
According to_____WHO, all big cities need health care plans to prevent_____spread of AIDS.
Xuzhou is a place with many forests. It is reported that nearly one-third of its land _________ covered with forests.
—Can you understand what I said, Ben? —No problem. I can ___________ follow you.
—What do you think of her teaching? —Great! No one teaches ____________in our school.
It’s dangerous __________ with the wild animal.