题目

下列变化过程中，需要吸热的是A．生石灰与水混合 B．天然气燃烧 C．浓硫酸溶于水 D．干冰气化  答案：D解析:略 — do you go for a trip with your family?—Once a week.A. How soon B. How farC. How often D. How long