题目

阅读理解 SCENE ONEMrs. Miller: (standing at the school gate) Good morning, children! (A shy boy walks up and looks nervous.) Nice to meet you, Scott!Scott: (surprised) Oh, you know me? Who are you?Mrs. Miller: Welcome to our school. I'm your head teacher. I know you are new here. Let me take you to the classroom.Scott: (unhappy) l don't want to leave my old friends.Mrs. Miller: Cheer up! You will have new friends here. Look, here's your classroom. SCENE TWOMrs. Smith: Hello! I'm Mrs. Smith. Scott: (speaking quietly) Hello.Mrs. Smith: We are talking about a story we've just read. Who c3．1993年，中国科学院上海原子核研究所制得了一种新的铂元素的同位素${\;}_{78}^{202}$Pt．制取过程如下：（1）用质子轰击铍靶${\;}_{4}^{9}$Be产生快中子；（2）用快中子轰击汞${\;}_{80}^{204}$Hg，反应过程可能有两种：①生成${\;}_{78}^{202}$Pt，放出氦原子核；②生成${\;}_{78}^{202}$Pt，同时放出质子、中子．（3）生成的铂${\;}_{78}^{202}$Pt发生两次衰变，变成稳定的原子核汞${\;}_{80}^{202}$Hg．写出上述核反应方程．