下例属于穗状花序的作物是（）A.小麦 B.蚕豆 C.马铃薯 D.豌豆

下列有关细菌的叙述中不正确的是                        ( ) 

A．细菌细胞有细胞壁，但没有叶绿体

B．细菌细胞没有成形的细胞核

C．大多数细菌属于生态系统中的分解者

D．所有细菌都能导致动植物和人患病

单项式2x²y的次数是：______．

II. 完形填空（共10题；每小题2分，满分20分）

阅读下面短文，掌握其大意，然后从21—30各题所给的A、B、C和D项中，选出最佳选项。

Married couples   21   more than their homes, cars and finances. They are also likely to have some of the same   22  , experts say. If one of them   23  from asthma (哮喘) , depression, high blood pressure or raised cholesterol n. (胆固醇) levels , his or her partner   24   be afflicted ( vt. 使苦恼,折磨) with the   25   illness , Julia Cox of the University in northern England said. Cox and her team said the most likely  26   for the shared diseases was environment. Married couples usually eat the same foods, are exposed to the same allergens (n. 过敏原) and often have similar exercise patterns, all of   27   contribute to ailments (n. 小病, 疾病) such as allergies, high blood pressure and raised cholesterol. The scientists     28     the medical history of 8,000 married couples, aged 30 to 74.     29    is known, the proper use should be     30   some efficient measures to stop this.

21. A. share            B. spare          C. own        D. use

22. A. cancer           B. diseases       C. ill              D. throat

23. A. keeps           B. goes           C. suffers           D. comes

24. A. should          B. shall            C. could      D. will

25. A. different        B. difficult        C. similar     D. same

26. A. season          B. promise         C. reason      D. approach

27. A. who             B. which           C. whose      D. that

28. A. studied          B. read           C. copied     D. understood

29. A. As              B. For            C. It          D. What

30. A. made to               B. made of       C. making of  D. to make of

下列关于近因的认定与保险责任确定的说法中，错误的是( )。

A．单一原因致损，且该原因属于保险风险，则保险人负赔付责任
B．多种原因致损，且多种原因均属保险风险，则保险人负赔付责任
C．连续发生的多项原因致损，若前因属于保险风险，后因属于除外风险，则保险人不负赔付责任
D．在一连串连续发生的原因中，有一项新的独立的原因介入，导致损失，若新的独立的原因为保险风险，则保险人负赔付责任

内因是条件，外因是根据。( )