世界上的火山和地震，大多发生在（　　）

顾炎武主张“以天下之权，寄天下之人”。这种主张

根据短文内容, 选择正确答案。

    Hi, I am Andy. I am in Class 3, Grade 7. Welcome to our classroom. Isn't it big and clean?

   We all have lockers (柜) in the classroom. The red lockers are girls'. And boys' lockers are yellow. Do you like the colours? I have a locker too. This one is mine (我的). I put many things in it. There are some comic books, a football, and a pair of shoes in it. Jack's locker is beside（在……旁边） mine. There are socks and some paper in it. That one is Tom's. There are many CDs and books in it. His glasses are in the locker too.

    What is in Mary's locker? There is a yellow bag in it. What's in the bag?  We don't know. I guess there are lots of snacks(零食) in it.

（Ⅰ）求证：平面EAC⊥平面PBC；

（Ⅱ）若PD∥平面ACE，求四棱锥E﹣ABCD的体积．