The sheer scale of the investment it took to begin commercial expansion at sea reflects the immensity of the profits that such East-West trade could create.

回答如下：以上为包含2个定语从句的主从复合句

句子结构为：名词+定语从句①+谓语+名词+定语从句②

句子的主干为：The sheer scale of the investment+定语从句①reflect+ the immensity of the profits +定语从句②

The sheer scale of the investment (which/that)it took to begin commercial expansion at sea reflect the immensity of the profits (that) the profits such East-West trade could create.

句子语法结构分析

主句的主语：The sheer scale of the investment（绝对的投资额）

修饰主句的定语从句：（which/that关系代词充当宾语可以省略） it took to begin commercial expanstion at sea（it 不是形式主语，而是指代某个事物，句子没有说明）（它开启海上商业扩张所需要的）

主句谓语：reflect(反映/表现显示)

主句的宾语: the immensity of the profits（巨大的利润/收益）

修饰主句宾语的定语从句:（that 关系代词充当宾语可以省略）the profits such East-West trade could create（这样的东西贸易可能创造的利润。

句子中文意思：它所开启海上商业扩张所需要的绝度投资额极大地反映了这样的东西方贸易可能创造出的巨大利润/收益.

The sheer scale of the investment it took to begin commercial expansion at sea

to begin commercial expansion at 是不定式作目的状语

The sheer scale of the investment 为先行词

(that/which) it took 为省略关系代词的定语从句

如果把it看作形式主语,其结构为下面句子

It took the sheer scale of investment to begin commercial expansion at sea .（特别备注：这已经是一个主语从句，后面不能在接谓语了.

这是一个完成句子，后面不可以再直接+谓语的结构

sheer

vt. （使）偏航，（使）转向

adv. 完全地，全然；垂直地，陡峭地

n. 舷弧；单锚系泊的船位；偏离的方向；船体型线

adj. 完全的，全然的；极薄的；几乎垂直地，陡峭的；绝对的

过去式：sheered 过去分词：sheered 现在分词：sheering 第三人称单数：sheers 比较级：sheerer 最高级：sheerest

【1】adj.(用于强调)纯粹的，完全的，十足的

His music is sheer delight

 听他的音乐完全是一种享受。

Sheer chance quite often plays an important part in sparking off an idea.

灵感的激发通常纯粹是靠运气。

acts of sheer desperation. 彻底绝望的行为

【2】adj.陡峭的;垂直的

There was a sheer drop just outside my window.

陡坡就在我窗户外面。

A young man plunged from a sheer rock face to his death.

一名男青年从陡峭的岩壁上坠崖身亡

【3】adj.极薄的;极轻的;精致的

sheer black tights. 极薄的黑色紧身裤

【4】steep, abrupt, sheer这些形容词均含“陡峭的，险峻的”之意。

steep： 指坡度向上逐渐增加的斜陡坡，强调险峻，暗示难于攀登。

abrupt： 着重指地形突然起伏，形成尖角状。

sheer： 指自始至终近于垂直的陡峭，不仅仅很难爬上去，甚至于不可能攀登。