Tibet receives foreign visitors from January to April each year.( )
A.thousand ofB.thousands of
C.several thousands
I _____ some washing when you called me last night.( )
A.was doingB.am doingC.were doing
Dad, I want to be a policeman in the future.
Work hard, _____ you will succeed.( )
A.orB.andC.but
_____ the mountain is, _____ the air is.( )
A.The highest, the thinnest
B.Higher, thinner
C.The higher, the thinner
It _____ me two hours to help Mary with her math last Saturday.( )
A.tookB.spentC.paid
It is very dangerous for us the mobile phone while crossing the street. ( )
A.answeringB.to answerC.answer