In jokes, the chicken only crosses the road. In Australia, cane toads (蔗蟾) use roads to tr

In jokes, the chicken only crosses the road. In Australia, cane toads (蔗蟾) use roads to travel.
A new study finds that Cane toads are using roads to spread across the continent.   They take shelter overnight close to the open corridors (走廊), and then hit the road each evening in their damaging way.
Cane toads were brought into Australia from Hawaii in 1935 to control the spread of beetles (甲虫) that were destroying Australia's sugar cane crop. They are now moving into new places at the speed of 30 miles a year.
Toads can grow as large as dinner plates and can weigh up to 4.5 pounds. Their heads and backsides are covered with rows of warts (疣). They are known to kill snakes, lizards and other animals, including pet dogs. They have no natural enemy in Australia.
According to a research, toads make slower progress through thick plants than along open spaces and they hop (跳) alongside roads and fences whenever possible. Toads use long corridors that are well-suited for them to travel long distances.
Another study recently found that toads have evolved (进化形成) longer legs in recent years and that this is also helping them in their spread.
Efforts to kill toads have been largely unsuccessful, although scientists tried their best.  
Another new finding suggests ways to slow down its population.  For example, roadside borders can be changed to make them less attractive to toads, or allowing thick plants to grow along the sides of highways, thus forcing toads onto the road of themselves.
【小题1】 Which would be the best title for the passage?A．Ways to kill cane toads in Australia.B．Cane toads have evolved a lot in Australia.C．Australian cane toads hit the road.D．Worse environment forces toads to travel.【小题2】 At first, cane toads were brought to Australia to    .A．kill snakes, lizards and other animalsB．stop pet dogs from spreadingC．protect the sugar cane cropD．hate a scientific research【小题3】According to the passage, the ways to slow down the population of toads are based on the fact that cane toads    .A．move slower through thick plantsB．have no natural enemy in AustraliaC．mainly live near the roadsideD．like traveling at night【小题4】The underlined word They in Paragraph 3 refers to “    ”.A．BeetlesB．Cane toadsC．Australia's sugar cane cropD．New placesC