题目

Tom arrived at the bus station quite early for Paris bus. The bus for Paris would not leave until five to twelve. He saw a lot of people waiting in the station. Some were standing in line, others were walking around. There was a group of schoolgirls. Their teacher was trying to keep them in line. Tom looked around but there was no place for him to sit. He walked into the station cafe. He looked up at the clock there. It was only twenty to twelve. He found a seat and sat down before a large mirror on the wall. Just then, Mike, one of Tom’s workmates, came in and sat with Tom.“What time is y如图是A、B、C三种物质的溶解度曲线，回答下列问题：（1）A物质在t3℃时溶解度为 ．（2）P点表示 ．（3）t1℃时，三种物质溶解度由大到小的顺序是 ．（4）如果A物质中混有少量B物质和C物质，可用 的方法得到较纯的A物质．