如果把小树的树皮剥掉，往往会造成小树死亡。主要原因是破坏了树皮中的（ ）

几千年来中国的厨艺最讲究的就是“火候”二字．现在市面上流行如图1所示的新型电饭锅，采用了“聪明火”技术，电脑智能控温、控压，智能化控制食物在不同时间段的温度，以得到最佳的口感和营养，其简化电路如图2甲所示．R₁和R₂均为电热丝，S是自动控制开关．把电饭锅接入220V的电路中，用电饭锅的“聪明火”煮米饭，电饭锅工作时的电流随时间变化的图象如图2乙所示．

园林工人在栽某些树之前，往往要除去树体的大量枝条与树叶，其主要目的是（　　）

    Henry and Bill are good friends, but they ____ （从不） see each other. They come from different ____ （国家）. Henry is from the USA, Bill is from England. They ____ （两者） have computers and talk on the Internet. Today they talk about how to keep in excellent ____ （状况）.

    Henry thinks doing ____ （锻炼） is good. He is a ____ （成员） of a sports club. His ____ （梦想） is to be a football player. He also thinks good eating habits are important. Fruit and vegetables are his ____ （最爱）. He doesn't eat fast food, though it ____ （闻起来） delicious. Bill ____ （赞同） with Henry. He often plays sports and eats healthy food, too.