1. This rabbit had no natural enemies in the Antipodes, so that it multiplied with that promiscuous abandon characteristic of rabbits.
natural enemies是指天敌。
so that在这里引导的是结果状语从句。有时so that也可引导目的状语从句。具体的区别方法在语法部分详细讲解。
2. Scientists discovered that this particular variety of rabbit (and apparently no other animal) was susceptible to a fatal virus disease, myxomatosis.
no other 没有别的
例句：The facts allow no other explanation.
事实不容许有其他的解释。
No other major insurer acts with equal restraint.
在同业中再没有其它任何一家保险公司有我们如此高的自制力。
3. Later it was found that there was a type of mosquito which acted as the carrier of this disease and passed it on to the rabbits.
act as 担任，扮演，充当，起……作用
例句：Then you have to act as a dishwasher yourself.
那么就由你来充当洗碗机吧。
This oil acts as a purgative/has a purgative effect.
这种油有催泻作用。
4. So while the rest of the world was trying to get rid of mosquitoes, Australia was encouraging this one.
get rid of 摆脱，除掉，扔掉，干掉，消灭
例句：We'll have to get rid of him he never does a stroke.
我们得把他弄走--他什么活儿都不干。
5. It later became apparent that rabbits were developing a degree of resistance to this disease, so that the rabbit population was unlikely to be completely exterminated.
It在这里是形式主语，真正的主语是后面that引导的从句。
be unlikely to 不可能……
例句：It is unlikely to rain/that it will rain.
不太可能下雨。
She is unlikely to market philosophical views.
她未必会兜售哲学观点。
resistance to sth 对某物的抵抗力
