1)brazil`s forests were being cleared at the rate of almost 7，000 square miles a year。(巴西的森林以每年近7，000平方英里的速度被清除。)

　　2)the children were helping me clear weeds from the garden. (孩子们在帮助我清除花园里的杂草。)

　　speed up是个常用短语，意思是increase the speed

　　1)tom speeded up and overtook his classmates. (汤姆加快了速度，赶上他的同学们。)

　　注意speed用在词组动词中时，其过去式和过去分词为speeded， 其他情况下，其过去式和过去分词为sped。

　　2)africa`s population growth speeded up. (非洲的人口增长加速。)

　　3)bad housing and poverty speed up the breakdown of family life. (恶劣的住房条件和贫困加快了家庭的破裂。)

　　表示“坐落于某地”时，locate常用在被动语态中，be located.in which they are located中的they指rainforests， which指nations。

　　1)the factory is located in the suburb. (那家工厂坐落于郊区。)

　　2)the hospital is located in the center of the city. (医院坐落于市中心。)

　　3.according to many scientists， the burning of rainforests is also directly contributing to the so-called greenhouse effect。

　　contribute to在本句中的意思是help to bring about (促战，造成)。如：

　　1)your suggestion will contribute to solving the problem. (你的建议将有助于解决这个问题。)

　　2)carelessness contributed to his errors. (粗心大意造成了他的错误。)

　　so-called用作形容词，意思是“所谓的”。如：

　　1)he was deceived by his so-called friend. (他被所谓的朋友骗了。)

　　2)the so-called christian even showed no love to his own children. (这个所谓的基督徒连对自己的孩子都没有爱心。)

　　effect在句中用作名词，意思是“效果，效应”，在第三单元中我们对名词effect和动词affect做过详细讲解，再请看几个例句。

　　1)the sound effect of this movie is great. (这部电影的音响效果很棒。)

　　2)excessive smoking will have a bad effect on your health. (吸烟过多将会给你的身体带来不良影响。)

　　3)too much rainfall affected the harvest. (过多的雨水影响了收成。)

　　4)i hope what i have said won`t affect your decision. (希望我的话不会影响你的决定。)

　　4.it is a medicine chest of unlimited potential。