右图是《集合》的知识结构图，如果要加入“交集”，则应该放在（   ）

根据短文内容，从方框中选择适当的词并用其正确形式填空，使短文通顺、意思完整，每空一词，每词限用一次。

    My name is Betty. I am twelve. I have some ____. We are middle school students. We are in Class Two, Grade Seven. This is Miss Green. She is an American teacher. She ____ us English. Her classes are very ____. We all like her.

    This is my new classroom. In the classroom you can see many ____ and chairs. A blackboard, a clock and a map ____ China are on the wall. On a desk, you can see some pencils. The red one is mine. The green one is ____.

    Look! You can see a ball under the desk. That's Kate's desk. The ball is____, too. This is my desk. You can see a ____on it.

如图，在梯形ABCD中，AD∥BC，AC⊥AB，AD=CD，cos∠DCA=$\frac{4}{5}$，BC=10，则AB的值是（  ）

“穿花蛱蝶深深见”、“青草池塘处处蛙”，这两句诗中描述的蛱蝶和蛙在生殖和发育方面的相似之处是（　　）