其中的一些，如蜗牛的腺粘液，很难获得，而且极其昂贵。
Some of these, such as the glandular mucus of snails, were difficult to obtain and outrageously expensive.
在北非的许多国家，如苏丹和利比亚，签证很难获得，而且这里给背包者的供应也很少。
In many countries in the north, such as Sudan and Libya, visas are hard to obtain, and there is little provision for backpackers.
缺乏资助的调控部门将很难获得最优秀的毕业生，而且对才华横溢的年轻人认为值得学习的事情影响也甚微。
Under-funded regulatory agencies will struggle to compete for the most talented graduates and will have only a marginal impact on what those talented young people think is worth learning.
这种迹象表明，变异不仅是非随机的、范围有限的，而且根本就是很难获得的。
The evidence suggests that not only is it nonrandom and parochial, but it is difficult to come by at all.
但是这种方法代价高，危险性大，而且很难选择或获得各种病变状态；
But this kind of method price is high, the risk is big, and very difficult choice or acquire every kind of pathological changes appearance;
他们从好书中不但得到乐趣，而且受到很多教益，他们从中获得的那种精神食粮，从其它地方是很难得到的。
From good books, moreover, they draw much besides entertainment. They gain mental food such as few companions can supply.
他们从好书中不但得到乐趣，而且受到很多教益，他们从中获得的那种精神食粮，从其它地方是很难得到的。
From good books, moreover, they draw much besides entertainment. They gain mental food such as few companions can supply.
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