tpo

At one time, the animals present in these fossil beds were assigned to various modern animal groups, but most paleontologists now agree that all Tommotian fossils represent unique body forms that arose in the early Cambrian period and disappeared before the end of the period, leaving no descendants in modern animal groups. At one time, the animals were assigned to animal groups,but most paleontologists now agree that all Tommotian fossils represent unique body forms that arose in the early Cambrian period and disappeared before the end of the period, leaving no descendants in modern animal

Only recently have investigators considered using these plants to clean up soil and waste sites that have been contaminated by toxic levels of heavy metals-an environmentally friendly approach known as phytoremediation.This scenario begins with the planting of hyperaccumulating species in the target area, such as an abandoned mine or an irrigation pond contaminated by runoff. Only recently have investigators considered using these plants to clean up soil and waste sites that have been contaminated by toxic levels of heavy metals-an environmentally friendly approach known as phytoremediation

Wind velocity also increase with altitude and may cause serious stress for trees,as is made evident by the deformed shapes at high altitude. Wind velocity also (with altitude) increase and may cause serious (for trees) stress ,as is made (by the (deformed )+(at high altitude)shapes ) evident. 风速 ( 随海拔 ) 增加并且风速造成 ( 对树的 ) 压力，这个作为 ( 可塑的且在高海拔的 ) 形态的 ) 的证明。 as is the case应理解为非限制性定语从句，as为关系代词，代表主句所表达的整个概念。以下例句均出自《英语As的用法研究》： As has been said before , grammar is not a set of dead rules.从前讲过，语法并不是一套死规则。 As is very natural , man can't live without air.没有空气，人就不能生存，这是十分自然的。 As is often the case , the