搜题请搜索小程序“爱下问搜题”
问题 选择题

除去下表所列物质中含有的杂质，所选试剂不正确的是（　　）

选 项物 质杂 质除去杂质所选试剂
A铜粉铁稀硫酸
B生石灰碳酸钙稀盐酸
C二氧化碳氧气灼热的铜粉
D稀盐酸稀硫酸氯化钡溶液
 

答案

答案：B

题目分析：A、铜粉不能与稀硫酸反应，铁能与稀硫酸反应，所以用稀硫酸能将杂质铁除去，故A试剂正确；B、生石灰和碳酸钙都能与稀盐酸反应，原物质与杂质都被除去了，故B试剂不正确；C、灼热的铜粉不能与二氧化碳反应，能与氧气反应，利用灼热的铜粉能将氧气除去，故C试剂正确；D、氯化钡溶液与稀硫酸反应生成了硫酸钡沉淀和盐酸，通过过滤得到了稀盐酸，故D试剂正确．

单项选择题

Phyllis Wheatley is regarded as America’s first black poet. She was born in Senegal, Africa, about 1753 and brought to America aboard a slave ship at about the age of seven. John and Susannah Wheatley bought her for three pounds at a slave auction in Boston in 1761 to be a personal servant of Mrs. Wheatley. The family had three other slaves, and all were treated with respect. Phyllis was soon accepted as one of the family, which included being raised and educated with the Wheatley’s twin 15-year-old children, Mary and Nathaniel. At that time, most females, even from better families, could not read and write, but Mary was probably one of the best educated young women in Boston. Mary wanted to become a teacher, and in fact, it was Mary who decided to take charge of Phyllis’s education. Phyllis soon displayed her remarkable talents. At the age of twelve she was reading the Greek and Latin classics and passages from the Bible. And eventually, Mrs. Wheatley decided Phyllis should become a Christian.
At the age of thirteen Phyllis wrote her first poem. She became a Boston sensation after she wrote a poem on the death of the evangelical preacher George Whitfield in 1770. It became common practice in Boston to have" Mrs. Wheatley’s Phyllis" read poetry in polite society. Mary married in 1771, and Phyllis later moved to the country because of poor health, as a teacher and caretaker to a farmer’s three children. Mary had tried to interest publishers in Phyllis’s poems but once they heard she was a Negro they weren’t interested.
Then in 1773 Phyllis went with Nathaniel, who was now a businessman, to London. It was thought that a sea voyage might improve her health. Thirty-nine of her poems were published in London as Poems on Various Subjects, Religious and Moral. It was the first book published by a black American. In 1775 Phyllis wrote a poem extolling the accomplishments of George Washington and sent it to him. He responded by praising her talents and inviting her to visit his headquarters. After both of her benefactors died in 1777, and Mary died in 1778, Phyllis was freed as a slave. She married in 1778, moved away from Boston, and had three children. But after the unhappy marriage, she moved back to Boston, and died in poverty at the age of thirty.

The underlined word "they" in Paragraph 2 refers to ______.

A．publishers

B．poems

C．children

D．black people
查看答案
填空题

常用的加热杀菌技术有：高温灭菌法、（）、超高温消毒法、微波加热杀菌。
查看答案