You are under no obligation to help as assistance is purely ______.
A.free
B.donated
C.charitable
D.voluntary

Scientists ______ a carefully controlled experiment on the mystery virus.
A.put up
B.set in
C.turned over
D.carried out

I've got lots of ______ but only a few really good friends.
A.neighbors
B.best friends
C.acquaintances
D.partners

Choose the underlined part that needs correction.You can congratulate (A) yourself (B) about (C) having done (D) an excellent job.
A.having done (D)
B.about (C)
C.yourself (B)
D.congratulate (A)

______ the parcel, he was surprised at what he saw.
A.Opening
B.Have opened
C.When opened
D.To open

I’m really looking forward _______ to university.
A.to go
B.
C.
D.go

If I _______ you were sick, I would have called sooner.
A.know
B.would have known
C.had known
D.knew

There’s ...... waiting outside to see you. She didn’t tell me her name.
A.anyone
B.someone
C.no one
D.everyone

If you walk on the stress before Tet, you’ll find great _______ everywhere.
A.excitement
B.exciting
C.excited
D.excitedly

__ ____ you change your mind, I won't be able to help you.
A.Because
B.Provide
C.Unless
D.If only