21.Instead，they tend to be endlessly recycled in the food chains
1）tend to do/be：be likely to do/ be 趋向……。往往……
eg：Prices are tending upward.物价趋于上涨。
In primary and secondary schools girls tend to work harder than boys.在小学和中学时，女孩比男孩用功。
2）be recycled ：使再循环；回收利用；重心利用
The recycled water is used to water plants.
4）be dependent on：依赖于
It is not good for students to be too dependent on their teachers
22.One might guess that this time Carson the reader might have reminded Carson the scientist of some passage in Shakespeare's most famous play.
remind sb of sth：make sb.think of sth.使人想起，提醒。
eg：Please remind me of getting up at 5 tomorrow morning.
The picture reminded me of my childhood in the village.
23.Prince Hamlet used revoltingly grisly images in the vicious baiting of his hatred uncle when he told him that in nature's food chain，the worm is king.
24.Rachel Carson know of this poisonous cycle.
know of：知道……的存在；听说 be aware of the existence of，hear about
eg：Do you know of any filling station around here？ 你知道这一带有加油站吗？
I don't know the writer，but I know of him.我不认识这个作家，但我听说过他。
25 And she knew now，as her own observations were confirmed by fellow scientists all over the country，that this “worm” now carried a heavy concentration
This view is confirmed by the fact that…这种观点以被…事实所证实。
The plan was approved by the Ministry of Communication.
2）concentration （concentrate）：集中、专心 指把人或物集中在一起，把精神，注意力集中在某一事物
Chess requires great concentration.下棋需要全神贯注。
The government put the revival of economy as the focus of its work.
26.It could be passed on to fish，to other animals，to their food supply and to men and women and children throughout the earth.
pass on （from…） to…：（及物） 把……（从……）传给；（不及物）（从……）转移到……
We hope Sino-Japanese friendship will pass on from generation to generation.
The money passed on from one to another until it reached the conductor's hands.
27.In spite of fierce opposition from the chemical industry，from powerful government agencies，and from organizations，shepersisted in her research and writing
persist in sth./doing sth.：不顾困难、他人反对 坚持做……有时指执拗地不听好言相劝，达到了使别人讨厌地固执已见的地步。
eg：He persisted in his folly despite his friend's advice.
So long as you persist in jogging，you will shed some weight.
insist on：to keep doing sth…
He insisted on the accuracy of his account
We insist that the DPRK's nuclear issue be resolved peacefully.
28.The book was exploded into he public consciousness.
explode into：develop 突然变成，发展成，演变成
The border incident exploded into a war between the two countries.那个边界事件突然演变成两国间的战争。
29.The little girl…had fired a major salvo in the battle for the environment
salvo：（n） the firing of several guns during a battle or as part of a ceremony