According to the passage, why should we consider using alternative energy sources ?
A.Because conventional energy resources are being depleted, and they cause environmental damage.
B.Because global warming has increased the amount of sunlight that reaches the earth.
C.Because they are free and available worldwide.
D.Because fossil fuels are no longer available.

Where is the best place in the passage to insert the following sentence:
" Although the US is not utilizing geothermal resources to this extent, the Western US has a similar capacity to generate geothermal power"
A.after the phrase " global scale"
B.after the phrase " by geothermal power"
C.after the phrase " earth-friendly"
D.after the phrase " growing steadily"

______(61)
A.others
B.The other
C.The others
D.other

______(63)
A.mixture
B.roll
C.connection
D.fix

______(64)
A.apart
B.instead
C.inside
D.aside

______(66)
A.puts
B.places
C.fits
D.adds

______(69)
A.turn
B.pass
C.set
D.blow

______(70)
A.same
B.then
C.too
D.so

It can be concluded from the passage that lighthouses with day- marker patterns would most likely be found in areas where_______.
A.the structure themselves cannot be easily seen by passing mariners
B.there are not many lighthouses
C.the weather is frequently bad
D.there are a number of lighthouses with similar structures

The author implies that, compared to those of the past, contemporary lighthouses ______.
A.require less maintenance
B.are more difficult to operate
C.are more romantic
D.employ more powerful lights