确定基坑开挖方案的依据主要有()和降排水要求。A.基坑支护结构 B.基坑平面尺寸 C

压块机手动操作中，主、侧缸行程只与（）和（）决定。

急发性溶血性输血反应的筛选／排除试验是（）.

A.Cooombs试验

B.Ham试验

C.Rous试验

D.PK活性定量测定

E.血红蛋白电泳测定

IV.阅读理解（共17小题；每小题２分，满分34分）

Like cats, geckos（壁虎）always land on their feet. If they happen to fall from a wall or leaf they’ve been climbing, a quick move of the tail makes sure that they always land on their feet first, a new study finds.

Geckos are truly built for climbing: their feet have hairy toes that can fix themselves to a wall or other vertical（竖直的）surfaces. However, geckos’ feet can’t always keep hold and they may fall to the ground. When geckos fall or jump off a wall, they always land stomach-side down. Geckos’ long tails become necessary during their falls, the new study shows.

Researchers did an experiment. They placed geckos up-side-down on the underside of a leaf. When they lost their foothold and fell, the geckos pitched （倾斜）their tails for balance. They then rotated（旋转）their tails to make their bodies rotate. As soon as they were right-side up, they stopped rotating. On average, it only took the geckos about a tenth of a second to right themselves so that they would land on their feet.

Cats use a different way to land on their feet after a fall. As their tails don’t have the power like geckos’ tails, cats can’t use them to right themselves. Instead they twist their bodies around mid-air.

Engineers are trying to build a robot that imitates the geckos’ climbing ability. A tail will be fixed to the robot to allow it to keep balance.

54. What do we know about geckos?

A. Their toes make it possible for them to walk on walls.

B. Their tails can fix them to a wall or other vertical surfaces.

C. They often land on their backs when they jump off walls.

D. It takes them a second to right themselves in mid-air.

55. How do cats avoid their injury during a fall?

A. By twisting their bodies.                 B. By fixing their toes to the ground.

C. By using their tails to right themselves.        D. By landing upside-down.

56. Geckos’ special abilities have given engineers some new ideas to _________.

A. allow robots to climb vertical surfaces       

B. reproduce geckos like robots

C. invent robots that can rotate on the ground

D. invent robots that can balance themselves using their tails

57. What is the text mainly talking about?

A. The interesting living habits of geckos.   B. The differences between cats and geckos.

C. Why geckos always land on their feet.      D. How geckos climb up vertical walls.

政治决策就是政府和政党等政治管理主体对政治生活的重大问题制定和选择行动方案的过程，它是对政治生活的方向、目标、原则、方法和步骤进行抉择的过程。下列不属于政治决策的特征的一项是( )。

A．政治性，主要涉及政治生活

B．指导性，它是关于政治管理的蓝图设计，决定着政治管理的整个实施过程

C．条款性，必定以很多条款来规定

D．权威性，它的行为主体政府给它带来了权威性

要约人在要约发生法律效力之前，欲使其不发生法律效力而取消要约的意思表示是（）。

A．新要约

B．要约撤回

C．要约撤销

D．承诺