（Ⅰ）若不等式f（x）≤m的解集为﹣1，5，求实数a，m的值；

（Ⅱ）当a=2且0≤t＜2时，解关于x的不等式f（x）+t≥f（x+2）．

   78.6－(56.3－42.6)×2.8=____

A、       B、        C、
最大的是____； 最小的是____．

阅读下面短文, 按照句子结构的语法性和上下文连贯的要求, 在空格处填入一个适当的词或使用括号中词语的正确形式填空。

    Sara and her father planned ____ trip to a mountain near their home. The path they chose____ (begin) at the foot of the mountain and led all the way ____ the top. Sara packed lunches earlier that morning. ____ (she) father filled their backpacks with other things and they  ____ (be) off!

    As they started up the path, Sara’s father pointed out many different____ (plant) that grew on the path. He showed Sara the ____ (different) between the____ (leaf) of trees.  Sara was glad ____ her father knew so much! She always learnt something whenever they went on a trip. This time, she was sure that she ____ learn more.

正方形不同于矩形的性质是（　　）