9.…which they badly need to pay off their foreign debts and purchase foreign equipment and other goods。
badly在本句中用作副词，意思是extremely。如：
1)i am badly in need of advice. (我急需建议。)
2)we need the money badly. (我们非常需要这笔钱。)
pay off的意思是pay all that is owed (清偿)。如：
1)it book him 6 years to pay off the debt。(他花了六年时间才还清那笔债。)
2)he won`t be able to pay off a home all his life. (他一辈子也不能付清购买住房所下的钱。)
equipment是不可数名词，不可在其后加s。
goods是复数名词，意思是“商品;货物”。
10.…how to select trees worth exporting and to cut only those trees down while leaving the rest， so that the basic make up of the forest would not be disturbed。
形容词worth后面通常接动名词或名词。如：
1)this book is worth reading. (这本书值得一读。)
2)the equipment is worth 10，000 dollars. (这台设备值一万美元。)
请注意区别worth，worthy和worthwhile：
1)be worth + n. = be worthy of + n。
this matter is worth consideration。
this matter is worthy of consideration。
2)be worth doing = be worthy of being done
to be done
this matter is worth considering。
this matter is worthy of being considered。
to be considered。
3)it is worthwhile doing sth。
to do sth。
it is worthwhile to consider the matter。
considering the matter。
make-up在句中用作名词，意思是“组成，构造”。如：
1)he didn`t know the make-up of the mineral. (他不知道这种矿物质的构成。)
2)the make-up of chinese characters is hard for many foreigners. (对许多外国人来说汉字的构造很难。)
make-up还可以表示“化妆”、“虚构”、“补考”。
11.last but not least， …
本句的意思是the last point but not the least important one (最后一点，但并不是最不重要的点。)
本课主要短语及表达
1.at such a rate