用计算器计算（﹣5）⁴﹣2×（﹣3）²，按键顺序及显示的结果为：5____ 　y²____ ﹣2×____ 　=____ ．

能使两个直角三角形全等的条件是（　　）

Chen Jie: Which season do you like best, Mike ?

Mike: I like summer best.  

Chen Jie: Why do you like summer?

Mike: Because I can eat ice-cream and swim in the lake.

Chen Jie: I don't like summer. It's too hot.  

Zang Peng: What's your favourite season?

Chen Jie: Spring. It's sunny and warm. I can plant trees and fly kites. How about you,

Zhang Peng?

Zhang Peng: My favourite season is winter.

Mike: Why do you like it?

Zhang Peng: Because I can skate and make a snowman. I like snow.

如图，是小彬利用标杆AB测量某建筑物高度的示意图，其中P，B，D在同一水平直线上，点P，A，C在同一直线上，AB⊥PD，CD⊥PD，测得标杆AB=1.5m，PB=2m，PB=6m，则该建筑物CD的高是____米．