简述土地革命的阶级路线、土地分配方法及意义。

In the United Statcs, there were  some well-constructed houses for native Indians, ranging from the simple brush shelter to the five-storied pueblo.

In the eastem United States, one of the existing types was that commonly know under the Algonkian name of wigwam in which the Iroquois Indians lived. The wigwams were of wagon-top shape with straight sides and ends, made by bending young trees to form the round shape. Over this shape pieces of tree bark were laid to protect the Indians from bad weather. Over the bark dried grass was added. A small hole allowde smoke to escape from the top. Doorways at each en served also as windows, The Iroquois Indians built trunk walls all around their villages. The wall had only one opening, They could quickly close this cpening if their enemies came near.

Interestingly, the Choctaw Indians in Mississippi also lived in a wigwam of a most primitive(原始的) construction, but different from those of the Iroquois Indians.The Choctaw Indians’wigwams, made from mud,cane and straw, were in the form of a bee-hive. The covering was made of a long, tough grass. A post in the centre supported the roof.A hole in the top admitted the light, and allowed the smoke to pass out.

The tipi tent-housing of the upper lake and plains area was put up with poles set lightly in the ground, tied together near the top, and covered with bark and grass in the lake country. It was easily portable, and two women could set it up or take it down within an hour.

The Pawnee, Mandan and other Indian tribes (部落) along the Missouri built solid ring-shaped structhures of trunk, covered with earth and dried grass,housing adozen families.

The Wichita and other tribes of the Texas border built large ring-shaped houses covered with dried grass.

Apart from the regular housing, almost every tribe had some style of housing.

72.Which of the follwing pictures shows the house for the Iroquois Indians？

73. According to the passage, the Pawnee Indians built their houses _____.

A. with openings in the trunk walls   B. large enough for several families 

C. in a ring shape with bark and mud  D.by bending young trees to form the shape

74.All the native Indian houses described in the passage were_____.

A.  of the same shape           B. covered with grass 

C.  built with a post in the centre  D. built with doorways at each end

75. The passage suggests that ________

A.all the native Indians built  trunk walls all around  their houses 

B.all the native Indian houses were built with poles tied together

C.the Iroquois Indians took safety into account while building their wigwams

D.the Choctaw Indians in Mississippi built their wigwams with straight sides and ends

治疗作用初步评价阶段，目的是初步评价药物的治疗作用和安全性（）。

A．Ⅰ期临床试验 

B．Ⅱ期临床试验 

C．Ⅲ期临床试验 

D．Ⅳ期临床试验 

E．生物等效性试验

一级负荷的供电原则是：两路（）供电，确保在故障情况下也能够（）供电，对两路电源的转换时间有要求。

以下疾病发病原因与日光照射有关的是（）

A.阿弗他溃疡

B.疱疹性口炎

C.盘状红斑狼疮

D.寻常狼疮

E.以上都不是

灌浆前钻孔冲洗的目的是什么？