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

During 1700s, Philadelphia developed into the wealthiest city in the American colonies.
A.during 1700s
B.developed
C.wealthiest
D.American

While we're on vacation, Mary will look after the dog.
A.If we go on vacation, Mary will stay at our house.
B.Mary will be looked after while we're on vacation.
C.Mary will take care of our dog while we're on vacation.
D.we're going to buy a dog for Mary after returning from vacation.

No one but the seven-year-old boy saw the terrible accident.
A.The seven year old boy saw no one in the terrible accident.
B.Only the seven year old boy saw the terrible accident.
C.No one in the terrible saw the seven year old boy.
D.No one at all saw the seven year old boy's terrible accident.

"I'm sorry I made a mistake." , said he.
A.He blamed you for making a mistake.
B.He told he had made a mistake.
C.He said he had made a mistake.
D.He apologized for making a mistake.

They say that employment is the most important thing to us.
A.It is said to be the most important thing to us.
B.Employment is said that it is the most important thing to us.
C.Employment is said it is the most important thing to us.
D.Employment is said to be the most important thing to us.

They spend half an hour to watch the news on T.V.
A.It spends them half an hour to watch the news on T.V.
B.It spends them half an hour watching the news on T.V.
C.It takes them half an hour watching the news on T.V.
D.It takes them half an hour to watch the news on T.V.

It was kind of Jane to send me flowers when I was sick.
A.I did not receive any flowers from Jane.
B.I appreciate Jane's sending me flowers when I was ill.
C.Jane was ill, so I sent her flowers.
D.I was kind enough to send Jane flowers.

What is the main topic of this passage ?
A.Examples of the use of energy sources worldwide.
B.How energy resources are tapped from nature.
C.The benefits of solar and wind power over conventional energy sources.
D.Two types of alternative energy sources that should be further utilized.