若9x2－kxy+4y2是一个完全平方式，则k的值（） A．6 B．±6 C．12

阅读理解。

     Venice is the "Queen" of the Adriatic Sea (亚得里亚海). Every year thousands of people from all over

the world travel to Italy to visit the city. Do you know why they like to go there for a visit?

     Venice is a very beautiful city. It is quite different from other cities in the world. There aren't any roads

and streets in the city. So there aren't any cars and buses. There are many canals (运河) in the city. There

is one big canal and one hundred and seventy-seven small canals. People move up and down the canals in

boats to go to work, go shopping or visit their friends.

     But Venice is sinking. It is going down and the water is going up. In 2040 Venice will be under water,

The Adriatic Sea will cover the city. The Venetians (威尼斯人) love their city and want to stay there. So

they want to save Venice from the sea. They do not want to leave. How can they save Venice? They can

build some strong huge walls and gates in the sea. The gates will close to keep too much water out. Thus

Venice will not sink.

1. From this short article we know Venice is  ________.

A. a very beautiful woman of the Adriatic Sea.

B. the most important woman in Italy.

C. a very important and beautiful place of the Adriatic Sea.

D. the most important city in Italy.

2. People from all parts of the world go to visit Venice because ________.

A. there are 177 canals in the city.

B. it is sinking into the Adriatic Sea.

C. there are a lot of kinds of boats on the canals.

D. it is not only beautiful but also quite different from other cities.

3. The Venetians usually go to work or visit their friends ________.

A. by bus.

B. by bike.

C. in cars.

D. in boats.

4. Year by year the Adriatic Sea ________ and Venice ________.

A. is rising…is sinking.

B. is going down…is going up

C. has risen… has sunk

D. will go up…will go do

5. Because the Adriatic Sea will cover it, the Venetians ________.

A. have to leave Venice in 2040.

B. will try to do something to save their city.

C. want to stay there until the water covers the city.

D. do not love the city any longer.

补写出下列名篇名句中的空缺部分。

（1）舳舻千里，旌旗蔽空，            ，横槊赋诗 。    （《赤壁赋》）

（2）水何澹澹，                 。                    （《观沧海》）

（3）角声满天秋色里，                。         （《雁门太守行》）

（4）                 ，都护在燕然。                 （《使至塞上》）

（5）                 ，却话巴山夜雨时。              （《夜雨寄北》）

（6）山河破碎风飘絮，                     。          （《过零丁洋》）

（7）纷纷暮雪下辕门，                     。           （《白雪歌送武判官归京》）

（8）元嘉草草，封狼居胥，                 。          （《京口北固亭怀古》）

关于骶棘韧带，哪项是正确的

A．位于骶骨与坐骨棘之间
B．位于骶髂关节与坐骨棘之间
C．位于骶尾关节与坐骨棘之间
D．其宽度即为坐骨切迹宽度
E．以上均不恰当

圆角半径分类及其作用有哪些？