如图，在边长为a的正方形中剪去一个边长为b的小正方形（a＞b），把剩下的部分拼成一个梯形，分别计算这两个图形阴影部分的面积，验证了公式　____ ．

阅读理解

　Scientists say life will be very different in 2050.

    First, there will be no TV channels(频道)in 2050. People will choose a program(节目)from a computer and watch it on TV. In 2050, we will get information from the computers only.

    Second, water will be a big problem in 2050. In many places, people won't have water to drink.

    Third, cars will use new and clean fuels and they will go very fast. There will be a computer in every car. And the computers will control the cars and there won't be any accidents(事故).

根据《必修三》古诗文内容，完成下列选择题。

将黑色公绵羊的体细胞核移入到一白色母绵羊去除细胞核的卵细胞中，再将此重组细胞植入一黑色母绵羊的子宫内发育，出生的小绵羊即是“克隆绵羊”．那么，此“克隆绵羊”为（　　）