如图的漫画《快撑不住了》，说明了我国（    ）

①人口老龄化问题严重              ②人口基数大、新增人口多

③计划生育基本国策已过时      ④必须完善社会保障体系

回答问题(简答)。

    Lucy is my good friend. She is eleven years old. She is a student. She likes singing. She has a nail pet. Her name is Kitty. Look, Lucy's singing and the cat is dancing. Lucy wants to be a singer when she grows up.

    Lucy's mother is a nurse. She works in a hospital. She likes shopping. She usually buys a lot of beautiful clothes at weekends.

如图，已知在Rt△ABC中，∠C＝90°，BC＝1，AC=2，则tanA的值为（     ）