$\sqrt{{\left(1\frac{2}{3}\right)}^2}+\sqrt{{\left(-1\frac{2}{3}\right)}^2}$ 的值是（   ）

下列事件中，必然事件是(    )

下列各式中，是3x²y的同类项的是（   ）

根据短文内容，判断句子正误。
    My friend Tom is a farmer. He has a farm. There are many animals on his farm. Ducks are yellow. They can swim. Rabbits are white. They can jump. Look! Cows are white and black. Where are sheep? Sheep are under a big tree. The dog can say "Woof, woof！"I like animals.

如图为12月22日甲乙丙丁四个城市昼夜长短示意图（阴影部分表示黑夜）．读图完成下题．