Allemande 應 該 以 咩 方 式 彈 奏 is the bst ?

This is a very difficult question. However, from reading your question, I suspect that you have unknowingly skipped some important steps. Yo ur question sounds a bit like someone asking how to drive fast without even knowing how to start a car. So let's back up a few steps.
First, when playing anything of Bach, you have to know what Bach was trying to write: what type of dance or keyboard genre, in what national style, imitation of string music, etc.. This is one of the most difficult aspects of deciphering Bach's music, and an aspect that you need to spend time studying and trying out on the piano. Your teacher should be able to help you with that.
After deciding on the style you can then decide on the type of articulations as well as tempo. 音程比較遠的音通常都會斷開 can be loosely taken as a general rule, but is not always true, such as in music that resembles an allemande. Obviously in an Air you are not going to mince your phrases in little bits and pieces. Also, if the notes form an important harmony, such as at a cadential point or at a hemiola, it may not be advisable to 斷開 too much.
Without knowing the character and style of the music you are simply taking a big risk. In conclusion, you have to first understand the character and style Bach was writing, then everything else will come naturally. For example, you discovered (after some lengthy studies) that one of the inventions is written in the style of a French courante, then immediately you'd know the tempo (triple time, not too fast) and the appropriate articulation (very slightly detached, a bit dry but not too much), as well as general character (heavier on 1st and 3rd beat, a bit more solemn than an Italian corrente). Many factors have to be taken into consideration before embarking on subjective interpretative issues.
Hope this helps!

濫用別人答案, 你覺得泰利文和巴哈是用同一種演奏方式嗎?

This is a very difficult question. However, from reading your question, I suspect that you have unknowingly skipped some important steps. Yo ur question sounds a bit like someone asking how to drive fast without even knowing how to start a car. So let's back up a few steps.

First, when playing anything of Bach, you have to know what Bach was trying to write: what type of dance or keyboard genre, in what national style, imitation of string music, etc.. This is one of the most difficult aspects of deciphering Bach's music, and an aspect that you need to spend time studying and trying out on the piano. Your teacher should be able to help you with that.