问题 单项选择题

β2肾上腺素受体激动剂基本结构,下列关于β2肾上腺素受体激动剂的叙述中错误的是()

A.β2肾上腺素受体激动剂基本上都具有β-苯乙胺的结构

B.氨基N上大多带有一个烷基.β-碳原子上带有一个羟基,苯环上不同位置通常带有各种取代基

C.沙丁胺醇是将异丙肾上腺素苯核3位的酚羟基用羟甲基取代,N原子上的异丙基用叔丁基取代所得

D.特布他林是将异丙肾上腺素分子中的邻二羟基改为间二羟基所得

E.班布特罗是指含有3'-甲酰胺基-4'-羟基苯环以及烷氧苯乙基的脂溶性结构

答案

参考答案:E

阅读理解

I travel a lot, and I find out different “styles”(风格) of directions every time I ask “How can I get to the post office?”

Foreign tourists are often confused(困惑的) in Japan because most streets there don’t have names; in Japan, people use landmarks(地标) in their directions instead of street names. For example, the Japanese will say to travelers, “Go straight down to the corner. Turn left at the big hotel and go past a fruit market. The post office is across from the bus stop.”

In the countryside of the American Midwest, there are not usually many landmarks. There are no mountains, so the land is very flat; in many places there are no towns or buildings within miles. Instead of landmarks, people will tell you directions and distances. In Kansas or Iowa, for example, people will say, “Go north two miles. Turn east, and then go another mile.”

People in Los Angeles, California, have no idea of distance on the map; they measure distance in time, not miles. “How far away is the post office?” you ask. “Oh,” they answer, “it’s about five minutes from here.” You say, “Yes, but how many miles away is it?” They don’t know.

It’s true that a person doesn’t know the answer to your question sometimes. What happens in such a situation? A New Yorker might say, “Sorry, I have no idea.” But in Yucatan, Mexico, no one answers “I don’t know.” People in Yucatan believe that “I don’t know” is impolite. They usually give an answer, often a wrong one. A tourist can get very, very lost in Yucatan!

小题1:When a tourist asks the Japanese the way to a certain place, they usually ______.

A.describe the place carefully

B.show him a map of the place

C.tell him the names of the streets

D.refer to recognizable buildings and places小题2:What is the place where people measure distance in time?

A.New York.

B.Los Angeles.

C.Kansas.

D.Iowa.小题3:People in Yucatan may give a tourist a wrong answer ______.

A.in order to save time

B.as a test

C.so as to be polite

D.for fun小题4:What can we infer from the text?

A.It’s important for travelers to understand cultural differences.

B.It’s useful for travelers to know how to ask the way properly.

C.People have similar understandings of politeness.

D.New Yorkers are generally friendly to visitors.

单项选择题