听力原文:M: How many literature courses have you taken at the University? W: I've only had one course each in American and British Literature. I wish I had had more, especially in other languages. Q: What are the man and woman discussing? (18)
【简答题】A、B、C、D、E五种元素为1~18号元素。已知:它们的原子序数依次增大,A、B两种元素的核电荷数之差等于它们的原子最外层电子数之和;B原子最外层电子数比其次外层电子数多2;C元素原子的电子层数及最外层电子数都比E元素的少1;D和E的原子序数之和为30。它们两两形成的化合物有甲、乙、丙、丁四种。这四种化合物中原子个数比如下表: 甲 乙 丙 丁 化合物中各元素原子个数比 A 和 C 1∶1 B 和 ...