题目

完形填空I work in a middle school.It is pleasant for me to plant in my free time. At the beginning of the schoolyear, I had an idea—what if my students used a classroom 1 to grow vegetables for our school lunches? Thestudents could 2 learn about plantingscience.I asked my headmaster 3 I could start a new plant lab garden (植物实验花园). I was only in my secondyear of 4, but she agreed.As soon as my students wentinto the classroom, they got 5. They all wanted to learn how to grow vegetables in this way ofindoor gardening called hydroponics (水培). This is great for areasthat don't如图所示，是我国88式主战坦克，其质量为40t，每条履带与地面的接触面积是2m2，该坦克具有潜渡功能．求：（1）该坦克在水平路面上行驶时，对地面的压强是多大？（2）若坦克在河流中潜渡时，坦克对水平河床的压力为105N，则坦克所受的浮力为多大？