Choose the correct answer to complete the following sentences.
How long ............... each other?
A.have you known
B.did you known
C.you have known
D.have you knew

Vaccinating is the best ___ of some certain infectious diseases.
A.prevent
B.prevention
C.preventing
D.preventer

___ is all that most human beings are looking for.
A. Happiness
B. Happy
C.Happily
D.Unhappy

The aim of the conference is to promote international ___.
A.friend
B.friendship
C.friendless
D.friendly

Mr. Pike invited some ___ to his house for dinner last night.
A.hosts
B.hostesses
C.guests
D.celebrators

It’s important for children to get a good ___.
A.educate
B.education
C.educator
D.educational

Sometimes he does not pay ___ to his teachers so he does not get high marks.
A.love
B.attention
C.expectation
D. tim

The boss allowed me to take a.... .
A.two weeks’ leave
B.two week’s leave
C.two weeks leave
D.two weeks’s leave

The Red Cross is an international organization that helps people who are suffering from the results of war, disease or ___.
A.victims
B.disasters
C.opportunities
D.conditions

____ is a situation in which large numbers of people have little or no food, and many of them die.
A.Disaster
B.Famine
C.Poverty
D.Flood