[单项选择]Ants first captured the attention of software engineers in the early 1990s. A single ant cannot do much on its own, but a group of ants (51) can solve complex problems. That inspired people like Marco Dorigo, who is one of the founders of a (52) known as group intelligence.
Ants are good at choosing the shortest possible route between a food (53) and their nest. This reminds us of a classic computational travelling-salesman problem. Given a list of cities and their (54) apart, the salesman must find the shortest route needed to visit each city once. As the number of cities (55) , the problem gets more complicated.
Ants solve their own problem using chemical signals called pheromones (信息素), when an ant finds food, she takes it back to the nest, (56) a pheromone trail that will attract others. The more ants that (57) the trail, the stronger it becomes. (58) , the pheromones evaporate (挥发) quickly, so once all
A. follow
B. lead
C. surround
D. avoid

[单项选择]Ants first captured the attention of software engineers in the early 1990s. A single ant cannot do much on its own, but a group of ants (51) can solve complex problems. That inspired people like Marco Dorigo, who is one of the founders of a (52) known as group intelligence.
Ants are good at choosing the shortest possible route between a food (53) and their nest. This reminds us of a classic computational travelling-salesman problem. Given a list of cities and their (54) apart, the salesman must find the shortest route needed to visit each city once. As the number of cities (55) , the problem gets more complicated.
Ants solve their own problem using chemical signals called pheromones (信息素), when an ant finds food, she takes it back to the nest, (56) a pheromone trail that will attract others. The more ants that (57) the trail, the stronger it becomes. (58) , the pheromones evaporate (挥发) quickly, so once all
A. by the way
B. as a whole
C. for some time
D. on the average

[单项选择] Car Pollution Jump in the car, start your engine and you’’re off. But do you give any thought to what’’s coming out of the tailpipe as you go about your drive Carbon dioxide is the dominant greenhouse gas that causes global warming. The effects of global warming are uncertain, but they potentially include disruption of global weather patterns and ecosystems, flooding, severe storm, and droughts. Carbon monoxide, when inhaled, combines with haemoglobin in our blood, impairing the flow of oxygen to our brain and other parts of the body. Carbon monoxide is colorless, odorless, and poisonous even to healthy people (at high levels). It can seriously affect people with heart disease, and can affect the central nervous system. Motor vehicles are the main source of carbon monoxide pollution in many countries. Sulphur oxides contribute to respiratory illness, particularly in children and the elderly, and aggravate existing heart and lung disease
A. Y
B. N
C. NG