【英语时差8,16】跷跷板-上
时间：2019-02-23 作者：英语课 分类：英语时差8，16
Remember seesaws 2? Those things were great. But there was often a problem. Suppose there’s a big kid on one side and a smaller kid on the other side. The seesaw 1 just stays in one position: big kid on the ground, smaller kid up in the air. No fun. After a few different tries, you probably realized that moving the big kid in toward the center made it possible to rock a little. Move the big kid even more and you can achieve balance. Now the seesaw works. What’s going on here? The answer is in the “center of mass.” The center of mass is a point somewhere along the plank 3 that holds the two kids where their average weight falls. If you can get the center of mass to be over the pivot 4 point, the seesaw will be balanced.
- Prices have gone up and down like a seesaw this year.今年的价格像跷跷板一样时涨时跌。
- The children are playing at seesaw.孩子们在玩跷跷板。
- The plank was set against the wall.木板靠着墙壁。
- They intend to win the next election on the plank of developing trade.他们想以发展贸易的纲领来赢得下次选举。