题目

He 可以作为核聚变材料，下列关于He的叙述正确的是（      ）A. He 和H 互为同位素  B. He 原子核内中子数为2C. He 原子核外电子数为2D. He 代表有2个质子和3个中子的氦原子  答案：C解析:略  Do you know his address？” “No, I also wish I _____ where he _____.”     A. knew, live                      B. knew, lives     C. know, lives                     D. know, lived