维生素A具有多烯醇的结构,下列哪种是其最稳定的结构() A.全反式 B.全顺式 C.

题型:单项选择题 A1/A2型题

问题:

维生素A具有多烯醇的结构,下列哪种是其最稳定的结构()

A.全反式

B.全顺式

C.2顺式

D.6顺式

E.4顺式

考点:初级药士药物化学药物化学题库
题型:单项选择题 A1/A2型题

___________ do you go to work? [ ]

A. Where

B. How

C. What

题型:单项选择题 A1/A2型题

In recent years, the black bear population in the US has risen. Forests once cleared for farming have started to grow back and black bears have returned to them. But the bears are finding that their forest habitat has changed. Instead of thick forests covering thousands of acres, bears now have neighbors nearby. Roads, homes, schools, and shopping centers have been built at the edge of their forest home. And with humans and bears trying to share the same space, problems arise.

Black bears usually prefer to avoid people, but their nose may lead them into trouble. Their normal diet includes nuts, insects, and plants. But given the opportunity, they will gladly help themselves to whatever they can find.

With the great sense of smell, the bears can sniff out a tasty treat 2 or 3 miles away. Food left out in a park or backyard is an invitation to dinner. And while raiding (劫掠) a cooler, bird feeder (喂鸟器), trash can, car, or even a home, they can do a lot of damage. When that happens, people get angry. If another solution doesn’t immediately appear, they often want the bears killed.

Bear Aware, Bear Wise, and Bear Smart are trying to keep that from happening. They want people to respect bears, not fear them, and are suggesting ways to reduce the chances of bears stopping by for a snack. They’re convincing (使相信) people that by following some simple steps, it’s possible to live peacefully with our wild neighbors.

小题1:More black bears have appeared in the US because__________.

A.farmers have grown more food

B.forests have increased in the US

C.people stopped killing black bears

D.roads were built nearer to the forests小题2:We learn from the text that black bears _________.

A.hate insects in forests

B.eat different foods

C.usually live in big groups

D.like to share space with humans小题3:The underlined words “sniff out” in Paragraph 3 probably means “________”.

A.to express a low opinion

B.to find something by chance

C.to refuse something in a proud way

D.to discover something by its smell

题型:单项选择题 A1/A2型题

下列()条件可导致磨煤要机跳闸。

A、加载油泵跳闸;

B、MFT首出;

C、磨煤机电机轴承温度>90℃;

D、RB未投,一次风机跳闸。

题型:单项选择题 A1/A2型题

伤寒最严重的并发症是

A.肠出血
B.肠穿孔
C.中毒性心肌炎
D.肺炎
E.伤寒肝炎

题型:单项选择题 A1/A2型题

( )指专营证券业务的金融机构。

A.证券发行机构
B.证券经营机构
C.证券监管机构
D.证券服务机构

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