Pollutionis the price we pay for an overpopulated, over industrialized planet.

Whenyou come to think about it, there are only four ways you can deal withrubbish: dump it, burn it, turn it into something you can use again,attempt to produce less of it.

Wekeep trying all four methods, but the sheervolume of rubbish we produce worldwide threatens to overwhelm us.

1）When youcome to think about it -這個it應該是指"Pollution"吧？書上翻譯成“當大家開始考慮垃圾問題時” -垃圾？是不是錯誤呢？這個sheer可以用強調的very,only,alone替換嗎？

2）there areonly four ways you can deal with rubbish - 感覺句子缺少成分？應該是 there are only fourways you can deal withrubbish ？

1 這個it應該指rubbish。假如只pollution，后面句子就與狀語前言不搭后語了，由于pollution不僅僅是垃圾，還有水污染、空氣污染。你可以理解這個it是前照應指代，指代后面的rubbish。sheer在此為強調意義，英文解釋為：used to emphasize the large amount, size, or degree of something。不要替換，你就老老實實的學習sheer在此的使用方法和意義，不然你永遠不了解怎么樣用sheer。詞典例句：

The sheer amount of work was staggering.

2 句子沒問題。You can deal with rubbish in four ways. 你感覺這個句子有問題嗎？