英语长难句分析

But navigation for a fish smaller than a dime in a dark, relatively featureless open  ocean is not easy, so they use sounds produced by the reef and its inhabitants for guidance.

句子主干是

But navigation is not  easy.

导航不容易

relatively featureless open  ocean

相对于没有开放特色的海洋来说

 a fish smaller than a dime in a dark

在黑暗中比十分硬币还要小的鱼

they use sounds

他们使用声音

produced by the reef

由暗礁产生的声音

and its inhabitants for guidance

its 在这里表示暗礁，翻译成：和它在暗礁上栖息的动物做向导

and 并列了两个词组，the reef and its inhabitants

翻译成由暗礁和它栖息地上的动物产生的声音作为向导

整句话翻译就是

在黑暗中，相对于没有开放特色的海洋来说，比十分硬币还要小的鱼导航是不容易的。所以他们利用暗礁和它栖息地上的动物产生的声音作为向导。

We get a misleading impression of the treatment's effectiveness: we incorrectly exaggerate its benefits; or perhaps even find incorrectly that an intervention was beneficial, when in reality it did harm.

看句子or并列两个句子，we incorrectly exaggerate its benefits; or we perhaps even find incorrectly that an intervention was beneficial, when in reality it did harm.省略了主语，主语相同

这里英语中：表示解释说明！

We get a misleading impression of the treatment's effectiveness

加粗的部分是修饰impression，前面是主句

We get a misleading impression// of the treatment's effectiveness: we incorrectly exaggerate its benefits; or perhaps even find incorrectly// that an intervention was beneficial, //when in reality it did harm

我们得到了一个治疗没有效果的误导性的印象，我们错误地夸大它的疗效（好处），或者说甚至错误的发现干预是有益的，在现实生活中它是有害的。

正确的翻译

我们得到一个对疗效误导性的印象：我们错误地夸大它的好处，或者当干预现实生活中有害时，可能我们却错误地认为它 是有益的。