There is ____ “f” and ____ “u” in the word “UFO”.
---How do you study for a test? ---________.
---Why don’t you listen to tapes to improve your listening skills? ---It’s _______ difficult for me ______ follow.
---I’m going to take my driving test this weekend. ---________.
You will fall behind others ____________ you work hard.
H7N9 bird flu is a virus can make people die. We’d better stay away from birds at present.