如图，已知四棱锥P﹣ABCD，底面ABCD为菱形，PA⊥平面ABCD，∠ABC=60°，E、F分别是BC、PC的中点．

（1）判定AE与PD是否垂直，并说明理由．

（2）设AB=2，若H为PD上的动点，若△AHE面积的最小值为$\frac{\sqrt{6}}{2}$，求四棱锥P﹣ABCD的体积．

亚洲是世界上面积____ 的大洲，亚洲西北以____ 、 ____ 、 ____ 、 ____与欧洲为界，西南以 苏伊士运河 与非洲为界，东北以____ 与北美洲为界．

    Here are five kinds of animals. Elephants eat plants and fruit. They like water. The zebra ____in Africa. It eats leaves and grass. There ____only about 1,800 ____ in China. They eat bamboo and plants. The tiger is in Asia. It is large ____strong. It eats meat. It is good at swimming. Monkeys live in Africa, Asia and America. They eat meat, leaves, fruit and ____eggs.