题目内容：

    Brown bears have stopped eating salmon（鲑鱼）in favor of elderberries after being forced to make a choice due to climate change. Warming temperatures mean that the berries are ripening earlier than usual, at exactly the same time as the freshwater streams on Alaska’s Kodiak Island are over flowing with salmon.

The island’s brown bears typically feed first on salmon in early summer, followed by elderberries later in the season, in late August and September.

“What you have is a scrambling of the schedule,” said William Deacy, a biologist at Oregon State University that studied the phenomenon.

“It’s essentially like if breakfast and lunch were served at the same time and then there is nothing to eat until dinner. You have to choose between breakfast and lunch because you can only eat so much at a time.”

The study found that during the unusually warm summer of 2014, the bears, which would traditionally kill up to 75 percent of the salmon, were nowhere to be seen near the streams. Instead, they were in the hills busy munching on berries, which contain less protein and therefore take less energy to break down, causing them to gain weight more quickly.

Biologists warned that changes caused by a warming planet were behind the bears’ unusual behavior and could affect the entire ecosystem.

The researchers found that the forests around the streams suffered because the bears’ fish carcasses（残骸）were no longer there to enrich the soil.

“Bears switched from eating salmon to elderberries, disturbing an ecological link that typically fertilizes the ecosystems and generates high death rates for salmon,” the study said. On average, red elderberries are said to be ripening two and a half days earlier every decade. If the pattern continues, they will regularly overlap（重叠）with the salmon by 2070.

1.Brown bears have begun to favor ________ because of the climate change.

A.salmon

B.elderberries

C.warm temperatures

D.fresh water

2.What does William Deacy mean by saying the underlined sentence?

A.Brown bears eat their breakfast and lunch at the same time.

B.We’re facing a hard problem with choosing the meals.

C.Climate change is disturbing the bears’ eating habits.

D.People’s biological clocks are changing regularly.

3.Which of the following words can best describe the phenomenon?

A.Natural. B.Unusual.

C.Amazing. D.Typical.

4.The finding of the study shows us that ________.

A.brown bears may become bigger and bigger

B.there will be a higher death rate for the salmon

C.red elderberries will probably be ripening in summer

D.the changes of bears’ behavior could affect the entire ecosystem