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8.1949年3月,毛泽东在中共七届二中全会的报告中提出的”两个务必”是指( )
a、 居安思危,增强忧患意识
b、 保持同人民群众的血肉联系
c、 保持谦虚、谨慎、不骄、不躁的作风
d、 保持艰苦奋斗的作风
选项 | 实验名称 | 试剂 | 作用 |
a | 影响酶活性的条件 | 质量分数为5%的盐酸 | 控制自变量—ph，为酶的作用提供酸性条件 |
b | 探究酵母菌细胞呼吸的方式 | 质量分数为10%的naoh溶液 | 吸收空气中的co2，保证通入酵母菌培养液中的空气不含co2 |
c | 低温诱导植物染色体数目的变化 | 质量分数为15%的盐酸 | 与酒精等体积混合，使植物组织中的细胞相互分离 |
d | 生物体维持ph稳定的机制 | 0.1mol/l的naoh溶液 | 与na2hpo4、nah2po4等溶液混合配制成ph＝7的缓冲液 |
a．a
b．b
c．c
d．d
discovery more without interest use widely along herself but tireless considered hard |
as a fossil(化石) scientist, mary anning made great contributions(贡献) to her field in the 19h century. her name is now 【1】 known in britain and even europe. but that was not always the case.
anning was a talented woman. she did not receive any proper education and taught 【2】 geology(地质学) and paleontology(古生物学).
anning grew up by the sea. at a young age, she showed great 【3】 in studying the fossils along the coastline. anning worked very hard. she went out in all weathers to search for fossils. at the age of 12, she uncovered a skeleton(骨架) that looked like a crocodile(鳄鱼). then, after ten years of 【4】 work, she made an amazing 【5】. it was a huge fossil of something that the world had never seen before.
however, many of anning’s findings disagreed with theories that had been widely accepted. what’s more, at that time, people had little respect for female scientists. anning’s findings were even published 【6】 her name. during her lifetime, the woman was never seriously 【7】 to be a scientist.
【8】 such troubles didn’t stop anning from making more discoveries. the woman was still keen on studying all sizes and types of fossils 【9】 the sea. her discoveries helped to prove the existence of some extinct(已灭绝的) animals. they formed the basis for charles darwin’s on the origin of species(《物种起源》).
in recent years, 【10】 people have come to realize the importance of anning’s work. she is now listed among the top ten british women who have greatly affected the history of science. anning was an ambitious and hard-working woman in history. she deserves to be remembered.
选项 | 实验名称 | 试剂 | 作用 |
a | 影响酶活性的条件 | 盐酸 | 控制自变量—ph，为酶的作用提供酸性条件 |
b | 探究酵母菌细胞呼吸的方式 | 氢氧化钠溶液 | 吸收空气中的co2，保证通人酵母菌培养液中的空气不含co2 |
c | 低温诱导植物染色体数目的变化 | 盐酸 | 与酒精等体积混合，使植物组织中的细胞相互分离 |
d | 生物体维持ph稳定的机制 | 氢氧化钠溶液 | 与na2hpo4、nah2po4等溶液混合配制成ph=7的缓冲液 |
a．a
b．b
c．c
d．d
选项 | 实验名称 | 试剂 | 作用 |
a | 影响酶活性的条件 | 质量分数为5%的盐酸 | 控制自变量—ph，为酶的作用提供酸性条件 |
b | 探究酵母菌细胞呼吸的方式 | 质量分数为10%的naoh溶液 | 吸收空气中的co2，保证通入酵母菌培养液中的空气不含co2 |
c | 低温诱导植物染色体数目的变化 | 质量分数为15%的盐酸 | 与酒精等体积混合，使植物组织中的细胞相互分离 |
d | 生物体维持ph稳定的机制 | 0.1mol/l的naoh溶液 | 与na2hpo4、nah2po4等溶液混合配制成ph＝7的缓冲液 |
a．a
b．b
c．c
d．d