题目

阅读理解 I noticed two male bluebirds. They appeared to be helping a female with a group of newly-born birds. I wanted to know if one of the males was an invader (入侵者). This is the fun of bird watching — you never know when you'll find something exciting and unusual. Like 90% of the bird world, one male bluebird pairs with only one female, and together they raise a family. But sometimes a third adult shows up and helps the pair raise the young. Often it is a relative. The most likely reasons a lone bluebird becomes a "helper bird" are that it either has lost its mate (配偶) or failed to get one during the mating season. Both the mated pair and the helper get some advantages when helping happens. Every time the helper brings food to the nest (巢), one of the parents is free to take care of its own needs for a few minutes. Helpers also protect the nest by driving away possible enemies. The helper's gain is less direct but equally valuable. He or she (helpers can be male or female) learns how to be a parent. Though raising babies is natural, skilled parents usually are more successful. The Florida scrub jay is a kind of bird living in the U.S. state of Florida. Many pairs of Florida scrub jays "have" one to six helpers. Usually the helpers are older children, and they do their job very well. Nests with helpers have 50% more young than nests without helpers (about half the jays don't use helpers). Helping in scrub jays seems related to a shortage of nesting habitats. Young jays must wait for older birds to die to get a nest. During the time, they help raise their younger brothers and sisters. （1） Why may a bluebird be a helper for other bird pairs? A . It has no mate of its own. B . It wants to be a parent itself. C . It wants to live in others' nests. D . It is good at raising baby birds. （2） What advantage does a helper bird get from being a helper? A . Practicing building nests. B . Being an experienced parent. C . Having its own needs satisfied. D . Finding a mate as soon as possible. （3） What can we learn from the last paragraph? A . Florida scrub jays are an endangered species. B . Some Florida scrub jays will die without a nest. C . Florida scrub jays need great help from humans. D . More young Florida scrub jays survive with helpers. （4） What is the main idea of the text? A . Bluebirds share nests. B . Animals are human-like. C . Helper birds feed and raise young of others. D . Bird watching brings people close to nature. 答案： A B D C

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