2020高考英語備考單元知識搜索與探究歸納Unit20 Scientists at work
解析:so...that...表示“如此……以至于……”，與句意最相符。
答案:a
歸納與遷移
(1)so +adj./adv.+ that...表示“如此……以至于”，that可省略；當so和它所修飾的形容詞或副詞放在句首時，主句倒裝。
the book is so interesting that i want to read it again. =so interesting is the book that i want to read it again.
這本書是如此有趣，以至于我還想再讀一遍。
there are so many mistakes in your article that i can’t understand the meaning. =so many mistakes are there in your article that i can’t understand the meaning.
你文章中的錯誤太多了，以至于我都無法理解其意思。
（2）在so...that句型中也可以使用名詞，結構如下：
so + few/many+可數名詞復數+that
so + little/much+不可數名詞+that
so +adj.+ a(n)+名詞+that=such + a(n)+adj.+名詞+that
it was so cold a day that the ice in the river was nearly two feet thick.=it was such a cold day that the ice in the river was nearly two feet thick.
天氣是如此之冷，以至于河里的冰結得都有兩英尺厚了。
it was such fine weather that the children all went out, playing in the sun.(weather為不可數名詞，所以前面不能加a)
天氣很好，孩子們都出去在陽光下玩耍。
there was so much water in the river that we couldn’t swim across it.
河水水位太高了，我們游不過去。