( )1.The Greens _____ China for seven years.
A.have come to B.have been to C.have come in D.have been in
( )2.Now most families have only one child _____ our country’s one-child policy.
A.so B.because C.because for D.because of
( )3.China has the _____ population in the world.
A.smallest B.most C.largest D.large
