Plastic
We use plastic wrap to protect our foods. We put our garbage in plastic bags or plastic cans. We sit on plastic chairs, play with plastic toys, drink from plastic cups, and wash our hair with shampoo from plastic bottles!
Plastic does not grow in nature. It is made by mixing certain things together. We call it a produced or manufactured material. Plastic was first made in the 1860s from plants, such as wood and cotton. That plastic was soft and burned easily.
The first modern plastics were made in the 1930s. Most clear plastic starts out as thick, black oil. That plastic coating inside a pan begins as natural gas.
Over the years, hundreds of different plastics have been developed. Some are hard and strong. Some are soft and bendable. Some are clear. Some are many-colored. There is a plastic for almost every need. Scientists continue to experiment with plastics. They hope to find even ways to use them!
考研考前必看高频词组(29)
考研考前必看高频词组(30)
考研考前必看十大范文责任/两代关系
考研考前必看高频词组(20)
考研英语词根大表
考研考前必看十大范文青年面对社会
考研考前必看高频词组(10)
考研考前必看高频词组(21)
考研考前必看高频词组(22)
考研必备词组(二)
考研考前必看高频词组(4)
考研考前必看十大范文职业道德
考研考前必看高频词组(14)
考研必备词组(四)
考研考前必看高频词组(27)
考研考前必看高频词组(31)
考研考前必看高频词组(7)
考研考前必看高频词组(17)
734条考研高频词组(八)
考研考前必看高频词组(3)
考研考前必看高频词组(18)
考研考前必看十大范文告示
考研考前必看高频词组(1)
考研考前必看高频词组(13)
734条考研高频词组(四)
考研考前必看高频词组(9)
考研必备词组(一)
考研必备词组(六)
734条考研高频词组(三)
考研考前必看高频词组(24)
不限 |
英语教案 |
英语课件 |
英语试题 |
不限 |
不限 |
上册 |
下册 |
不限 |