问题 选择题

除去下列物质中少量杂质(括号内为杂质)的方法中,不正确的是(  )

选项物质(括号内为杂质)除杂方法
AKNO3溶液(K2SO4加入适量硝酸钡溶液
BCaO (CaCO3高温煅烧
CCaCl2溶液 (盐酸)加入适量的Na2CO3
DCO2   (水蒸气)通过浓硫酸

A.【无选项】

B.【无选项】

C.【无选项】

D.【无选项】

答案

A、硫酸钾与硝酸钡反应生成硫酸钡沉淀和硝酸钾,进行过滤即可除去硫酸钡沉淀,剩余的都是硝酸钾溶液了,故A说法正确;

B、碳酸钙高温煅烧生成氧化钙和二氧化碳,二氧化碳跑掉了,剩余的是氧化钙,故B说法正确;

C、盐酸与碳酸钠反应生成氯化钠水和二氧化碳,引入了新的杂质,故C说法错误;

D、浓硫酸具有吸水性,可以把水蒸气除去,故D说法正确.

故选C.

阅读理解

E

There is a debate going on in America public schools over the best way to teach English to foreign students. Many schools use bilingual education. This means that students study their core subjects such as science, mathematics and social studies in their native tongues. They also take a few h ours of English.

Recently, many educators have begun to criticize bilingual education. Opponents claim that bilingual education slows not only students’ development of language skills but also their adjustment to American life. They often remain separated from the mainstream student body.

These critics have proposed the immersion method (沉浸式语言教学法). This means that students take only English classes until they can function effectively in regular subject classes. Proponents of the immersion theory argue that in order to prepare these foreign students for college or the job market, they must be able to communicate in English.

Despite this disagreement, nearly all educators agree that English is a necessary tool for improving the quality of one’s life in America.

72. In bilingual education programs, students ______.

A. study in their native countries

B. study their core subjects in their native languages

C. study only English until they can function effectively in regular subject classes

D. mainly work on adjustment to American life

73. A proponent is someone who ______.

A. supports a certain idea or policy      B. is against a certain idea or policy

C. uses the immersion method of teaching English   D. is a school administer

74. According to the article, which of the following is NOT true?

A. Nearly all educators agree that English is important for foreign students.

B. Students in bilingual education programs are often separated from American students

C. Nearly all educators agree that bilingual education is best for teaching English to foreign students.

D. Students with good English language skills have better chances for college or the job market.

75. What is the author’s opinion about the bilingual education in America?

A. He is for it strongly             B. He is against it strongly

C. He doesn’t show his own opinion  D. He is against all the educators

判断题