题目

 She__________ Robert for ten years. A. married    B. married with  C. has been marrying    D. has been married to 答案：C用NA表示阿伏加德罗常数的值．下列叙述正确的是A.标准状况下，密度为ρg?L-1的某气体纯净物一个分子的质量为B.17g甲基（-14CH3）所含电子数为7NAC.1mol C6H14分子中共价键总数为20 NAD.常温下，0.2molCl2溶于等体积水中，转移电子数为0.2 NA