在一定温度下，反应A₂(g)+B₂(g)2AB(g)达到平衡的标志是

阅读理解
    Mr. Black is American, but he is in Canada now. He is a tall man with funny glasses. He works in a big city but lives in a town far away. He lives on the twentieth floor of a building. Every morning he gets up early. Then he gets into the lift and it takes him down to the first floor. He runs to the bus stop and catches the early bus. It usually takes him about two hours to get to the factory by bus. Then he gets off the bus and walks into the workshop(车间) quickly. He starts his work at eight in the morning.

下图为我国某地示意图，读图回答下列问题。

看图，深林里大约住着300只 ，住着只200 ，森林里大约住着这两种鸟一共有多少只？

下列物质：①蔗糖　②麦芽糖　③淀粉　④纤维素　⑤油脂　⑥蛋白质，在酸存在的条件下分别进行水解，其水解的最终产物一定只有一种的有（　　）