it was considered a great honor to be part of his expeditions 中，it 是形式主语，真正的主语是 to be part of his expeditions。it is considered + adj + to do 意为「做某事被认为是……的」。

Below are some of Blackborow's diary entries 使用完全倒装：方位副词（Below）+ 系动词（are）+ 主语（diary entries）。当表方位的副词位于句首时，主谓完全倒装，使上下文衔接更紧密。

I was so enthusiastic about the idea...that I secretly went aboard his ship 使用 so...that... 结构，意为「如此……以至于……」。so 修饰形容词/副词，that 引导结果状语从句。

We saw the ship get crushed by the ice 中，see + 宾语 + do（原形）表示看到全过程。此处用 get crushed（被动），相当于 see the ship being crushed。感官动词后接动词原形（看全过程）或现在分词（看正在进行的动作）。

too dangerous and difficult for all of us to make it 使用 too...to... 结构，意为「太……以至于不能……」。for all of us to make it 是不定式的逻辑主语，表示「对我们所有人来说太难了以至于无法完成」。

Without Frank and Ernest, we'd all be dead by now 使用含蓄虚拟条件句，Without... 相当于 If we had not had Frank and Ernest，表示与过去事实相反的假设。主句用 would have done 或 would be done（这里用 we'd all be dead 表示状态）。

What if they were delayed? 意为「如果……怎么办？」，是 What would happen if... 的省略形式。此处使用虚拟语气（were），表示对将来的假设。

There were no trees growing on Antarctica 中，growing on Antarctica 是现在分词短语作后置定语，修饰 trees，相当于 trees that grow on Antarctica。

If it weren't for sea animals, we would all starve 使用与现在事实相反的虚拟语气：If + 主语 + were（过去式），主语 + would + 动词原形。If it weren't for... 意为「要不是因为有……」。

as dangerous to become too hot...as to become too cold 使用 as...as 同级比较，意为「太热和太冷一样危险」。注意两个 to become 不定式结构对称。

such relief and joy that many of us could not hide our tears 使用 such...that... 结构，意为「如此……以至于……」。such 修饰名词，that 引导结果状语从句。对比：so + 形容词/副词 + that。