George would certainly have attended the meeting _______.
A.if he didn’t get a flat tire
B.if the flat tire didn’t happen
C.had he not had a flat tire
D.had the tire not flatten itself

While the language barrier was once an obstacle to trade,______‘
A.the technical case is now no more
B.the case doesn’t longer exist
C.which is no longer the case
D.the technical hurdle is now the case

_________I came to see her yesterday, she was reading a book.
A.Before
B.When
C.While
D.After

___________(27)
A.all
B.every
C.any
D.some

It doesn’t cost much to run a solar power system.
A.A solar power system is quite cheap to set up.
B.Running a solar power system costs nothing.
C.A solar power system costs so much to run.
D.Running a solar power system is not costly.

__________(52)
A.consent
B.lead
C.undertake
D.tend

__________(54)
A.urge
B.press
C.insist
D.direct

What is an example of precipitation ?
A.wind
B.lightening
C.rain
D.thunder

__________(49)
A.information
B.layout
C.assembly
D.pattern

__________(50)
A.value
B.rate
C.ensure
D.determine