The girl is wearing a blue dress is my sister.( )
whom
which
who
Our country is taking action to ______ air pollution.( )
A.cut downB.cut upC.cut outD.cut off
The girl in the classroom ______ be Sarah.She has gone to the library.( )
A.mayB.mustC.can'tD.needn't
We have worked so long.Shall we stop ______ a rest?( )
A.haveB.to havingC.havingD.to have
Rules are helpful to us,______ we have to follow them.( )
A.soB.butC.orD.because
Tim is going to give his father a surprise ______ Father's Day.( )
A.inB.atC.onD.by