Helium is not inflammable, __________therefore safer than hydrogen.




A.that is
B.and is
C.but is
D.and it

A.summertime
B.vigorous
C.consensus
D.populate

A.merchandise
B.prosperous
C.tolerant
D.musician

______(79)




A.charge
B.payment
C.expensive
D.cost

______(72)




A.invent
B.discover
C.establish
D.modernize

Not until I was on my way to the airport that I realized I had left my passport at home.




A.Not until
B.on my way
C.that I realized
D.at home.

By being absent so often Paul failed the examination.




A.Being absent so often caused Paul fail his examination.
B.Paul failed his examination although he was absent quite often.
C.Paul's failure in his examination accounted for his frequent absences.
D.Paul's frequent absences cost him his chance of passing the examination.

-“Don’t fail to send your parents my regards.” -“___________”




A.You’re welcome
B.Good idea, thanks
C.Thanks, I will
D.It’s my pleasure

______(39)




A.grounds
B.results
C.factors
D.means

_________(6)




A.anywhere
B.whatever
C.everywhere
D.anyway