题目

— This photo makes me think of _________________ trip to the Great Wall last year. — Yeah, we had a great time there. A . a B . an C . the D . / 答案：C以下验证“盐酸中哪种粒子使紫色石蕊试液变红色”的实验设计不合理的是（ ）A．水不变红色不变红色红色B．稀HCl变红色红色褪去C．D．