Therefore 及 Thus 都是副詞，兩者意思和用法有些分別。
THERFORE 的用法比較單一，主要是用來帶出前述句子的結果，解作 " 因此 " " 所以 "。
例﹕She is good at singing and therefore she won a lot of prizes in different singing contests.
THUS 有幾種意思，第一種意思與 Therefore 差不多。
例﹕We had no electricity, and thus we had to light candles last night.
第二種意思是 " 這樣 " 或 " 以這種方式 "
例﹕You make lift heavy things thus to protect your spine.
第三種用法跟 " so far " 差不多，用 " thus far " 來表示 " 直到目前" 或 " 到某一程度 "
例﹕Scientists are thus far unable to solve the problem of global-warming.
2007-03-19 17:27:52 補充：
例﹕You must lift heavy things thus to protect your spine.There is a typing mistake. Sorry!
thus & therefore are roughly the same...
you can choose either one.
Thus - 如此,這樣
Therefore - 因此;因而;所以