变量控制是化学实验中常用的设计方法．在探究影响不同固体物质在溶剂中溶解限量的因素时，不需要控制的变量是（　　）

仙人掌的叶呈刺形，这是对什么环境的一种适应（    ）

根据短文内容，从短文后的选项中选出能填入空白处的最佳选项，并在答题卡上将该项涂黑。每个选项限选一次。

Teacher: What do you want to do in your future?

Lily: I like shopping and talking to people. ____ Maybe selling clothes is a good business for me.

Ryan: My hobbies are playing computer games and making friends online. ____ I guess I will learn more about computers and make super-smart computer programs.

Bill: My parents have kept lots of pets since I was little. ____ Those stories have always stayed in my mind. One day, I will share them with people by drawing and writing books.

Anna: Though my mom and two sisters are all doctors, I'm sure I will stay as far away from a hospital as I can. ____ I'll keep strong by playing my favorite sport, tennis, every day. One day I'll join the national team.