题目

He was more certain of it than of anything in the world. He had been told by his parents and grandparents that he must fall in love and really know a person before becoming ________.A.fascinated B.concernedC.committed D.exhausted 答案：【答案】C【解析】考查动词词义辨析。句意：他对这件事比世上任何事情都更有把握。他的父母和祖父母曾告诉他，在做出承诺之前，他必须坠入爱河，真正了解一个人。A. fascinated着迷；陶醉；B. concerned关心；C. committed承诺；委托；D. exhausted耗尽；用尽。根据句意可知选C。下列说法正确的是(设阿伏加德罗常数的数值为NA                A．在常温常压下，16gO2和O3的混合气体所含原子数目为NA B．1mol/LK2SO4溶液所含K+数目为2NA C．在标准状况下，22.4L水所含分子数目为NA D．7.8gNa2O2与CO2完全反应时，转移电子数目为0.2NA