Reading passages

221- According to the passage, the reason why dam building was started to be taken seriously is that ..............
A) if floods were to be prevented, dams would be more necessary than anything else
B) in Europe, new techniques in dam-building were devised
C) until then, they were thought as potentially dangerous
D) people didn't have enough experience to build formidable ones
E) industrialization made people feel the necessity of water to run machines
222- It is implied in the passage that ............ .
A) engineers in ancient Rome didn't use their talents, for they were underpaid
B) there were structures in ancient Rome reflecting the excellent talent of their designers
C) Roman engineers were lucky in that their designs had already been tested earlier
D) no dam was built in Europe till 550 AD
E) building techniques in ancient Rome was poor
In a popular sense, "insect" usually means the familiar pests or disease carriers. Many insects, however, are beneficial from a human viewpoint; they pollinate plants, produce useful substances, control pest insects, act as scavengers, and serve as food for other. Furthermore, insects are valuable objects of study in elucidating many aspects of biology. Much of our knowledge of genetics has been gained from fruit fly experiments and of population biology from flour beetle studies. Insects are often used in investigations of hormonal action, nerve and sense organ function, and many other physiological processes as well.
223- The passage is mainly about ............... .
A) the benefits of insects, contrary to the negative assumptions about them
B) the methods to get rid of pests in farming
C) the importance of insects in food production
D) a new type of insect employed in genetics
E) the relationship between insects and physiological processes
224- All the following benefits of insects are referred to by the author except the fact that they ............... .
A) help to eradicate harmful insects
B) are eaten by other insects
C) are used in hormonal experiments
D) eat the remains of plants and animals
E) are believed to have curative powers