You should do as I tell you. 和 They danced as I had asked. as 在這二句中做連接詞,而這二句似乎有東西被省略了,想請問一下為什麼這二句可以這樣寫?

1. You should do as I tell you (to do).
as = in the same way as

2. They danced as I had asked (them to dance).
as = in the same way as

英文有不重複的習慣，所以相同的內容在可以意會的狀況下會被強制省去。

Do as you are told. =照被吩咐地去做。（叫你怎麼做，你就怎麼做。）
省略told後面的to do
請參見<新世紀英漢辭典>p.1421 tell vt 說明2 tell +受詞+to do
He told me not to drive too fast.

［單字］as~ 按照~，依照~
［翻譯］ You should do as I tell you.
你必須按我説的去做。
They danced as I had asked.
他們按照我要求的去跳。
［文法］如您所言，as在這二句中做連接詞,但是並沒有語彙被省略。“as+分句”是固定結構，意為“按照分句”