题目

阅读理解。Have you ever dreamed about sending a letter to yourself or your friends in the future? While express mail(快递) is a fast way to send your letters, there is another type of mail appearing in China as a new business—future mail.“The letter should be sent next Mother’s Day and not a day earlier!” Lin Xiaofan, a college student in Shanghai, tells one of the companies offering the service.Lin Xiaofan wrote the letter to her mother nearly a year earlier to express her love to her mother for next Mother’s Day.“Offering this service makes people slow down and lets them u一定温度下，浓度均为0.1mol/L的下列溶液中，含H+离子浓度最小的是（ ）A.CH3COOHB.H2SO4C.HNO3D.HCl