如图所示是一个半径为R的圆形轨道，一辆小车沿着圆形轨道从a点运动了半个圆周到达b

DDZ-Ⅲ型的基型调节器由指示单元和（）单元两部分组成。

A、控制

B、运算

C、放大

D、报警

尿素合成中，氨的供体是（）

A.组氨酸

B.α酮戊二酸

C.谷氨酸

D.天冬氨酸

E.酪氨酸

如图所示，闭合电键S，灯L₁、L₂正常发光，由于电路出现故障，突然发现灯L₁变暗，电流表读数变小，则故障可能是

A．R₁断路

B．R₂断路

C．R₃短路

D．R₄短路

Thousands of puffins(海鹦) live in Maine and on islands in the Gulf of Maine. But the puffins may be in danger. Last summer, the percentage of laid eggs that successfully produced baby puffins took a dive. Scientists also found a decline in the average body weight of the adult and baby puffins on Machias Seal Island, home to the area’s largest colony. Over the winter, dozens of the seabirds from the region were found dead, likely from starvation.

What’s causing the puffin trouble? Scientists think it may be a shortage of food. With ocean temperatures rising, fish populations have moved around. Normally, puffins’ primary food source is herring, a type of fish. A lack of herring in the area could be causing the problem.

Butterfish from the south have become more abundant in the Gulf of Maine and could be a new food source for birds. But Steve Kress says butterfish may be too big and round for baby puffins to swallow.

Puffins spend most of their lives at sea. They come ashore to breed each spring and return to the ocean in August. The chicks swim to sea about 40 days after hatching. Puffin populations stretch across the North Atlantic, from Maine to northern Russia.

Maine’s puffin population has been at risk in the past. In the 1800s, they were hunted for their food, eggs and feathers. By 1901, only one pair of puffins remained in the state. Thanks to the help of local lighthouse keepers and seabird restoration programs, the state’s puffin population has been restored to more than 2,000 birds.

Scientists aren’t sure what will happen to the Gulf of Maine’s puffins. The birds may move further north. Kress says he hopes the Gulf population will sustain itself and then he continued. “You never know what climate change will bring,” Kress said. “Historically fish could move out and more southerly fish could move in, and puffins may adapt to the new fish. Only they will know how the story will unfold.”

小题1:The underlined phrase “took a dive” means _______.

A．increased

B．arose

C．reduced

D．changed小题2:In the scientists’ opinion, ________ is contributing to the puffin trouble.

A．a lack of herring

B．environmental pollution

C．the increase of birds

D．the huge size of butterfish小题3:It can be inferred from the passage that _______.

A．Maine’s puffin once nearly became extinct

B．Maine’s puffins’ eggs were of high prices

C．baby puffins grew up quickly

D．the number of Maine’s puffins is worrying小题4:Judging from Kress’s words in the last paragraph, we know ________.

A．climate change matters little

B．there is cause for concern

C．the new fish won’t harm puffins

D．puffins may move to the south小题5:How is the second paragraph mainly developed?

A．By giving examples.

B．By making comparisons.

C．By following time order.

D．By asking questions

肉类被炭疽杆菌污染，必须在什么时间内采取措施（）

A．6小时以内

B．8小时以内

C．10小时以内

D．12小时以内

E．14小时以内