as low as :

as+形容詞+as
as...as意為"和……一樣"，表示同級的比較。使用時要注意第一個as為副詞，第二個as為連詞。其基本結構為：as+ adj./ adv. +as。例如：

(1)This film is as interesting as that one.這部電影和那部電影一樣有趣。

(2)Your pen writes as smoothly as mine.你的鋼筆書寫起來和我的一樣流暢。

其否定式為not as/so +adj./ adv. +as。例如：

This dictionary is not as/so useful as you think.這本字典不如你想象的那樣有用。

若有修飾成分，如twice, three times, half, a quarter等，則須置于第一個as之前。例如：

Your bag is twice as expensive as mine.你的袋子比我的貴一倍。

since:

譯作“自從…以來”
(1)接時間點：如 I have stayed in that country since 1995. 要求：謂v.用現在完成時，而且須是延續性動詞。
(2)接一段時間 + ago：
如 They have lived in that house since two years ago. 要求：謂v.用現在完成時，而且須是延續性動詞。
(3)接時間狀語從句：
如 I have loved her since I met her last time. / Lily has stayed at home since she left school.
要求：主句的謂v.用現在完成時，而且須是延續性動詞；從句的謂v.用一般過去時，而且須是終止性動詞。
(4)用于句型“It’s / It has been + 一段時間 + since + 時間狀語從句”中，譯作“自從…以來, 已經…”。
如 It’s / has been three months since he moved to this city.
要求：主句的謂v.用一般現在時或現在完成時；從句的謂v.用一般過去時，而且須是終止性動詞。
(5)用于句型“一段時間 + has passed since + 時間狀語從句”中，譯作“自從…以來,…(時間)已經過去了”。 Three months has passed since he moved to this city.
要求：主句的謂v.用現在完成時，而且動詞必須是has passed；從句的謂v.用一般過去時，而且須是終止性動詞。
(6)注：當since用于否定句時，主句的謂v.可以是終止性動詞。
如 He hasn’t seen the film since last month.
(7)相關詞組：“從那時起”：ever since、since then、from then on.
注：ever since作為一個詞組，放句尾可單獨使用。如I have given up smoking ever since. 另外，還可在since后接句子。since前加ever，只是加重語氣而已。
如 I have given up smoking ever since I caught a bad cough.
(8) since還可引導原因狀語從句，譯作“由于；因為”，相當于because。如 Since he was lazy, he didn’t finish his homework.