5．What are the speakers mainly talking about?

       A．A best - seller author.

       B．The woman' s new book.

       C．A wedding reception.

4．What is the probable relationship between the speakers?

       A．Doctor and patient.

       B．Teacher and student.

       C．Policeman and driver.

3．What does the man suggest the woman do?

       A．Take more rest．          B．Talk to her boss．          C．Give up her job

2．Where are the speakers?

       A．In a library．             B．In a hospital．           C．In a classroom.

1．What happened to the woman yesterday?

       A．She missed the dinner party.

       B．She was angry at the dishes.

       C．She was hurt by the man.

       答案是B。

       A．￡19.15.                        B．￡9.15.                          C．￡9.18.

   （2）质量为m₁的He核，以速度v₀轰击质量为m₂静止的质量数为14的氮核，发生了核反应，最终产生两种新粒子A和B。其中A为O核，质量为m₃，速度为v₃，B的质量为m₄。

        ①写出核反应方程式；

②计算粒子B的速度v₄。

D．将辐射光子，光子的频率为