I'm Tom. I have a friend. Her name is Lucy. She is ____.Her favourite food is ____. She is thirsty. She would like some ____ .Her water bottle is ____the table. Look! There is her photo ____the table.
已知Rt△ABC中，∠C=90°，CH⊥AB于点H，AC=3，CH=2，求BC的长．
8-7=____
