继代培养次数越多，变异率越高。

根据短文内容，按要求答题。

Today is August 17^th. It’s my sister Mary’s ninth birthday. 73In the morning, my parents take us to Heima Clothes Store. There my mother buys a red sweater for Mary. After that we go to Huaxing Bookstore. At the bookstore, I buy some CDs for Mary. My father buys a book for her. Its name is Harry Potter. It’s Mary’s favorite book.

74In the afternoon, my parents have a party in our home for Mary. Mary’s friends Mike, Jim and Cindy come to the party. Mike brings a new pencil case to Mary. Jim gives Mary a soccer ball. My sister likes playing soccer. Cindy gives Mary an English-Chinese dictionary. At the party Mary is very happy. Oh, do you know me? I’m Mary’s brother. My name is Nick.

（一）根据短文内容简要回答下列问题。

小题1:How old is Mary?

__________________________________

小题2:Does Nick’s sister like playing soccer?

_____________________________________

（二）将短文中划线的两个句子译成汉语。

小题3:                                     

小题4:                                     

（三）请给短文拟一个适当的标题。

小题5:                                     

研究电场能的性质时，一般选无限远处为零势点，现将一个电子从电场中的a点移到无限远处，电场力做功6eV，则电子在电场中A点的电势能、A点电势分别为（　　）

A．6eV、6V

B．6eV、-6V

C．-6eV、6V

D．-6eV、-6V

You’ll have an English exam tomorrow. You’d better ____ watch TV this evening.

A．to not

B．not to

C．don’t

D．not

（16分）如图所示，质量为的木板A静止在光滑水平面上，其右端与固定挡板相距，内壁光滑的弹射器利用压缩弹簧把质量为的物块B（视为质点）水平向右弹射出去，B弹出后从A左端的上表面水平滑入，之后立刻拿走弹射器。已知A足够长，B不会从A表面滑出，A与挡板的碰撞无机械能损失；弹射器弹簧储存的弹性势能为，重力加速度为，不计空气阻力。

（1）B从A左端的上表面水平滑入时的初速度大小

（2）若A与挡板碰撞前，A、B已相对静止，求A碰撞挡板前的速度

（3）若A与挡板只发生一次碰撞，求A、B之间的动摩擦因数满足的条件。

下列批准文号格式中，哪一个是省级卫生行政部门批准的治疗性药品？（）

A.“省（简称）＋卫药准字＋（年号）第××号”

B.“省（简称）＋（年号）第××号”

C.“（年号）卫药准字Z－××号”

D.“（年号）卫药准字X－××号”