信息的基本概念在于它的（）。
参考答案：不确定性
Mr Smith was________to be a doctor but he became a teacher when he grew up. [ ]
A. demanded
B. supposed
C. suggested
D. agreed
配制标准缓冲液与溶解供试品的水，应是新沸过的冷水，其pH应为
A．3.5～5.5B．5.5～6.5C．6.0～7.0D．5.5～7.0E．5.5～9.0
