红松播种苗如何越冬防寒？

阅读短文，根据短文内容填上正确的单词  

    During his life Dr James Naismith worked as a doc-tor, taught P.E. and wrote several books. While he never thought it very important, Dr Naismith is today best known for one thing. He was the inventor of basketball.    

    Dr James Naismith was born in Canada in 1861 and his first job was at a special sports school in the USA.One day the school principal told James he was having a problem with the .students. Because of heavy snow, the students could not go outside. He told James that they needed a sport the boys could play indoors and gave the teacher two weeks to think of something.      

    It was on the very last day that James came up with  his idea. The" birth of basketball "is said to be on Decem- ber 21,1891,when two teams from the school played the first game. It was quite different from the basketball games of today. It had 9 players on each team and foot- balls were used instead of basketballs. Soon after, the game changed t0 5 players on each side, using special  " basketballs" through nets.     

   Although Dr Naismith did not live to see basketball become the worldwide game it is today, in 1936,just three years before his death, basketball became an Olym- pic sport. at the games in Berlin.  

1. Dr Naismith is ________ ________as the inventor of bas-ketball.

2. December 21,1891 was said co be the ________of bas-ketball.  

3. Today basketball has become the________ game.  

4. Dr Naismith died at the age of ________ .

5. Basketball became an________ sport at the games inBerlin in 1936.

下列有关地球自转和公转的说法错误的是（　　）

A．公转的周期为一年

B．地球围绕太阳公转

C．自转的方向是自西向东

D．自转产生四季现象

发电机进相运行时，如果低励限制器动作将（）励磁。

A.增加

B.降低

C.不变

D.其他三个选项都不是

高压无气喷涂设备的使用始于20世纪（）年代。

A.50

B.60

C.70

D.80

长度为n的顺序存储线性表中，当在任何位置上插入一个元素概率都相等时，插入一个元素所需移动元素的平均个数为 【5】 。