The first Earth Day also came at a time when a wave of legislation was being passed in the US, including the Clean Water Act, Clean Air Act and Endangered Species Act - the next 10 years were seen as the "environmental decade" because of such measures and the focus on green issues....
Every year, humans destroy approximately 10 million hectares of trees, a land area roughly the size of Portugal.人类每年摧毁约1000万公顷的树木，大致相当于葡萄牙的国土面积。By destroying the world's forests, humans are eradicating one of the planet's primary carbon sinks.由于对森林的毁坏，人类正在...
the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points.“the 1960s scientists … determined the age of the solar system to be at least a billion years”
The world is struggling to manage growing piles of plastic waste, and a new report is bringing to light the problem of burning plastics. Annually, the world produces 440 million tons of plastic each year, but the majority of plastic is often tossed in the trash. CBS News senior national an...
In the last 500 million years, there have been five times when life on Earth has almost ended. A 2015 study by scientists 1 were based on Brown University and Duke University in the US, look at 2 quickly species die out due to natural causes. They found that human activity is causing ...
The Earth is about 4,600 million years old. People live here for only 35,000 years. But we change the Earth in many ways. Many things we do are good, but some are not good for the Earth. A lot of people, birds and fish die each day because of water pollution. Factories pollute ...
Hidden in a steep-sided valley, fenced off by four cliffs, their hometown was secluded for hundreds of years. To reach the nearest town, the locals had to spend more than three hours clambering over hill and dale, following paths only suitable for foot traffic. ...
However, due to irrational development, because the waste of natural resources, global ecological damage, pollution of all kinds more serious. Now, the world each year 600 million hectares of land become desert, 20 million hectares of forests are disappearing, the average of one hour there is ...
Dinosaurslivedonearthmorethansixtymillionyearsago.Thiswasalongtimebeforepeopleexisted.Thereweremillionsofdinosaurs.Theylivedeverywhere.Somewereassmallaschickens.Otherswereasbigastenelephants.Somedinosaurshadwingsandcouldfly.Manydinosaurswereharmless.Theywereasgentleassheepandateplants.Otherswereharmful.Theywerefiercer...
解析 【答案】have been【详解】 考查therebe句型和时态。 句意:在过去的5 亿年里,地球上有五次生命几乎灭绝。 根据 时间状语In the last 500 million years可知, 句子用现在完成时。 此处考查there be句 型, 主语five times为复数形式, 助动词用 have。 故填have been。