问题 选择题

隐形眼镜洗液有效成分是过氧化氢(H2O2),有关过氧化氢正确的是(  )

A.它由氢气和氧气组成

B.它由氢元素和氧元素组成

C.它由1个氢分子和1个氧分子构成

D.它由2个氢原子和2个氧原子组成

答案

A、过氧化氢中含有氢元素和氧元素,但是不含有氢气和氧气,故A错误;

B、过氧化氢是由氢元素和氧元素组成的,故B正确;

C、过氧化氢分子中含有氢原子和氧原子,但是不含有氢分子和氧分子,故C错误;

D、由化学式的含义可知,分子是由原子构成的,物质是由元素组成的,故D错误.

故选B.

单项选择题

Culture is the sum total of all the traditions, customs, belief and ways of life of a given group of human beings. In this sense, every group has a culture, however savage, undeveloped, or uncivilized it may seem to us.
To the professional anthropologist, there is no intrinsic superiority of one culture over another, just as to the professional linguist there is no intrinsic hierarchy among languages.
People once thought of the languages of backward groups as savage, undeveloped form of speech, consisting largely of grunts and groans. While it is possible that language in general began as a series of grunts and groans, it is a fact established by the study of "backward" languages that no spoken tongue answers that description today. Most languages of uncivilized groups are, by our most severe standards, extremely complex, delicate, and ingenious pieces of machinery for the transfer of ideas. They fall behind the western languages not in their sound patterns or grammatical structures, which usually are fully adequate for all language needs, but only in their vocabularies, which reflect the objects and activities known to their speakers. Even in this department, however, two things are to he noted: 1. All languages seem to possess the machinery for vocabulary expansion; either by putting together words already in existence or by borrowing them from other languages and adapting them to their own system. 2. The objects and activities requiring names and distinctions in "backward" languages, while different from ours; are often surprisingly numerous and complicated. A western language distinguishes merely between two degrees of remoteness ("this" and "that"); some languages of the American Indians distinguish between what is close to the speaker, or the person addressed, or remote from both, or out of sight, or in the past, or in the future.
This study of language, in turn, casts a new light upon the claim of the anthropologists that all cultures are to viewed independently, and without ideas of rank or hierarchy.

The example of American Indian languages in the passage is to illustrate that______.

A.American Indian languages are not backward

B."backward" languages are borrowing from other languages

C."backward" languages may possess quite complicated vocabularies

D.western languages may also borrow from "backward" languages

选择题