________ is not clear to researchers.
A.Why did dinosaurs become extinct
B.Why dinosaurs became extinct
C.Did dinosaurs become extinct
D.Dinosaurs became extinct

Drinking water ________ excessive amounts of fluorides may leave a stained or mottled effect on the enamel of teeth.
A.containing
B.including
C.made up of
D.composed of

Newspaper publishers in the States have estimated __________ reads a newspaper every day.
A.nearly 80 percentage of the adult population who
B.it is nearly 80 percent of the adult population
C.that nearly 80 percentage of the adult population
D.that nearly 80 percent of the adult population

The works of such men as the English philosophers John Locke and Thomas Hobbes helped pave the way for academic freedom in the modern sense.
A.terminate
B.prevent
C.initiate
D.lighten

Many scientists agree that global warming poses great threats to all species on Earth.
A.risks
B.annoyances
C.fears
D.irritations

In some countries, the disease burden could be prevented through environmental improvements.
A.something to stiffer
B.something enjoyable
C.something sad
D.something to entertain

According to the first three paragraphs, technological tools that were designed to make our lives easier______
A.have not interfered with our privacy
B.have turned out to do us more harm than good
C.have brought us complete happiness
D.have fully met our expectations

Which of the following is NOT true about technological tools, according to new surveys?
A.They are being increasingly used.
B.They are used even during vacations.
C.They make our life more stressful.
D.They bring more leisure to our life.

Ann: More coffee? Anybody? Ben: __________
A.I don't agree. I'm afraid.
B.I'd love to.
C.Yes, please.
D.It's right, I think.

The brothers __________ most of the buildings in the street before long.
A.are owning
B.are going to own
C.will have been owning
D.will be owning