题目

We provide summer English courses which are the best you can find. You will enjoy coming to Los Angeles to learn about America n culture and improve your English at the same time. The course last for four, six or eight weeks. They start at the beginning of July and August. Out teachers are well-trained and very experienced. They teach English classes for four hours a day. You can choose between small groups of two or three, or large groups of up to 15. We provide weekly tests to see the progress you’re making with your language skills of reading, writing, speaking and listening. We al 如图，Rt△ABC中，∠C=90°，BC=8cm，AC=6cm．点P从    B出发沿BA向A运动，速度为每秒1cm，点E是点B以P为对称中心的对称    点，点P运动的同时，点Q从A出发沿AC向C运动，速度为每秒2cm，当    点Q到达顶点C时，P，Q同时停止运动，设P，Q两点运动时间为t秒． （1）当t为何值时，PQ∥BC？ （2）设四边形PQCB的面积为y，求y关于t的函数关系式；并说明四边形PQCB    面积能否是△ABC面积的？若能，求出此时t的值；若不能，请说明理由； （3）当t为何值时，△AEQ为等腰三角形？（直接写出结果）