僵局,垃圾场,地球日,黑色星期五。The story goes that police in Philadelphia didn't like all the traffic and shoppers on the day after Thanksgiving, so they called it Black Friday.据说费城警察不喜欢感恩节后一天的交通和购物者，所以他们称之为“黑色星期五” 。Tis the season of shopping.这是购物...
In most conifers and a few angiosperms, the main stem or leader outgrows and subdues the lateral branches beneath, givingrise to a cone-shaped crown with a central trunk. This is called an excurrent branching habit. ... The growth habit that a tree will develop can be determined soon a...