斑蝥中斑蝥素的含量测定采用 A．重量法 B．硝酸银滴定法 C．紫外-可见分光光度法

From the earlier time it was well ___1___ to the Peruvians that when a cut ___2___ made in the thick skin of a ___3___ tree, a white liquid like milk came ___4___. From this fluid (流动的) a sticky ___5___ of rubber might be made. This rubber is ___6___ and wax-like when warm so that it is ___7___ to give any form.

The Peruvians ___8___ the discovery that it is very good for ___9___ out water. Then in the early ___10___ of the century they made overshoes to ___11___ their feet dry. Then a certain Mr Mackintosh ___12___ coats of cloth which were ___13___ with rubber. Today Mackintosh raincoats are still ___14___ after him.

But these first rubber shoes ___15___ raincoats were unpleasantly soft and sticky in ___16___. They were also stiff and very ___17___ in winter. They were like wax(蜡) although they ___18___ a bit stronger.

But the rubber ___19___ use today has been improved. It is ___20___ sticky but soft and elastic(弹性的) and strong enough for any season.

1. A. talked     B. heard  C. seen    D. known

2. A. has  B. was     C. may    D. will

3. A. rubber    B. apple  C. orange       D. oak

4. A. from      B. through      C. out     D. up

5. A. raincoat  B. shoes  C. border D. mass

6. A. hard       B. fast     C. stubborn     D. soft

7. A. important      B. impossible  C. possible      D. uncertain

8. A. made      B. found  C. wrote  D. neglected

9. A. finding   B. keeping      C. making      D. pouring

10. A. kind     B. part    C. sort     D. halves

11. A. clean    B. clear   C. keep   D. prevent

12. A. made    B. found  C. appeared    D. gave

13. A. full      B. like     C. lined   D. applied

14. A. looked  B. named C. made  D. searched

15. A. or B. and     C. with    D. but

16. A. today    B. summer      C. winter D. rain

17. A. soft      B. sticky  C. elastic D. cold

18. A. felt       B. made  C. needed       D. produced

19. A. Mr Mackintosh    B. the Peruvians     C. we      D. is

20. A. also      B. always       C. neither       D. not

碱性＝2.0的渣称为（）。

A．酸性渣

B．中碱性渣

C．高碱性渣

社会保险区别于雇主责任保险的突出特点是______。

A．统一筹措保险资金

B．共同承担风险

C．更有效的保障工人的利益

D．分担企业的责任

剪刀：布匹( )

A．玻璃：门窗

B．锯子：木头

C．衣服：缝纫机

D．门窗：玻璃

男性，67岁，无牙颌。全口义齿摘戴时疼痛，定位明确，戴入后无明显不适。其疼痛的原因是（）

A.骨隆突处未缓冲

B.基托不密合

C.基托边缘过长

D.基托进入组织倒凹

E.基托组织面有小结节