用两步滴定法滴定阿司匹林片的含量，是因为（） A.方法简单，结果准确 B.片剂中有淀

世界上往往把下列哪一项作为评价一个国家和地区的环境质量标准[ ]

A．自然资源的保护状况

B．“三废”的处理情况

C．人均绿地占有率

D．是否有环境保护法律

美感是（）

A、一种概念的逻辑判断

B、由强调情感的中介的一种具有审美趣味的判断

C、一种赏心悦目，怡情悦性的心理状态

D、人对美的认识、评价与欣赏

在灌注模型时，先加水与硬质石膏调和，灌注印模的组织面；稍后调和熟石膏灌注其他部分。发现熟石膏结固太慢，以后调和熟石膏时在水中加入了少量白色晶体

所使用熟石膏的特征表现在

A．其晶体构型为α型

B．其结固反应为放热反应

C．其生石膏含量多，结固减慢

D．其结固反应为吸热反应

E．其调和速度愈快，结固愈慢

无菌治疗盘有效期为（）小时。

A、4

B、2

C、24

D、72

Under pressure from animal welfare groups, two national science teachers associations have adopted guidelines that ban classroom experiments harming animals. The National Association of Biology Teachers and the National Science Teachers Association hope to end animal abuse in elementary and secondary schools and, in turn, discourage students from mishandling animals in home experiments and science fair projects.

Animal welfare groups are apparently most concerned with high school students experimenting with animals in extracurricular projects. Barbara Orlans, President of the Scientists’ Center for Animal Welfare, said that students have been performing surgery at random, testing known poisonous substances, and running other pathology experiments on animals without even knowing normal physiology.At one science fair, a student cut off the leg and tail of a lizard to demonstrate that only the tail can regenerate, she said. In another case, a student bound sparrows, starved them and observed their behavior.

"The amount of abuse has been quite horrifying," Orlans said.Administrators of major science fairs are short-tempered over the teachers’ policy change and the impression it has created. "The teachers were sold a bill of goods by Barbara Ortans," said Thurman Grafton, who heads the rules committee for the International Science and Engineering Fair. "Backyard tabletop surgery is just nonsense. The new policies throw cold water on students’ inquisitiveness," he said.

Grafton said he wouldn’t deny that there hasn’t been animal abuse among projects at the international fair, but he added that judges reject contestants who have unnecessarily injured animals. The judges have a hard time monitoring local and regional fairs that may or may not choose to comply with the international fair’s rules that stress proper care of animals, Grafton said.

He said that several years ago, the Westinghouse Science Talent Search banned harmful experiments to animals when sponsors threatened to cancel their support after animal welfare groups lobbied for change.

The teachers adopted the new policies also to fend off proposed legislation--in states including Missouri and New York--that would restrict or prohibit experiments on animals.

Officials of the two teachers organizations say that they don’t know how many animals have been abused in the classroom. On the one hand, many biology teachers are not trained in the proper care of animals, said Wayne Moyer, executive director of the biology teachers’ association. On the other, the use of animals in experiments has dropped in recent years because of school budget cuts. The association may set up seminars to teach better animal care to its members. (414 words)

Notes: pathology 病理学。lizard 蜥蜴。tabletop 桌面。short-tempered 脾气急躁的。lobby for 游说支持。fend off 躲开。

Thurman Grafton suggests that（）

A. animal abuse is horrible and should be terminated

B. the teachers have been compelled to do all animal experiments

C. prohibition of experiments on animals will discourage students from being curious

D. the international science and Engineering Fair will cease to operate because of the new policies