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）質量為m₁的He核，以速度v₀轟擊質量為m₂靜止的質量數(shù)為14的氮核，發(fā)生了核反應，最終產生兩種新粒子A和B。其中A為O核，質量為m₃，速度為v₃，B的質量為m₄。

        ①寫出核反應方程式；

②計算粒子B的速度v₄。

D．將輻射光子，光子的頻率為