I am always cofused by fit and suit.

I don’t know how to choose for those sentence below:

這件衣服的（尺寸、顏色、款式）很適合你。

什麼時間適合去拜訪你。

這個字適合用在這個句子嗎？

..............

這兩個字都可作 "適合" 講，但用法不同： 如果指衣物的大小很適合用 fit；若是指式樣、顏色很適合用 suit。如： 
(1) These shoes don't fit me; do you have a larger size?
(這雙鞋〔或這些鞋都〕不適合我〔太小〕，有沒有更大的?)
(2) Red and black are colors that suit me very well.
(紅色和藍色是很適合我的顏色。)
(3) Do you think this style suits me?
(你認為這個式樣適不適合我?)

source from :http://tw.letter.yahoo.com/one/latest.php?letter_id=31&d=2004-07-12&old=18#2

Kathy, thanks a lot.

My Mom bought me a new T-shirt, it reminds me of the question I once had.

I asked mother’s friend, Melody, she told me by E-mail like this:

The difference between "fit" and "suitable" here is that "fit" is used if you want to ask if the shirt is OK in terms of size (it's not too big and not too small). "Suitable" would be used if you wanted to ask if the shirt would be appropriate for the event where it will be worn--for example, the shirt would not be "suitable" for a fancy dinner with Ma Ying-Jeoh and Chen Shui-bian, but it is "suitable" for your Sports Day.

Is it an answer for me? No, she gave no answer. It’s a joke.

suit
Ex:你適合這件洋裝。
→You suit this dress. ＊

中文語法常說某人「適合」某樣東西，例如你很適合這件衣服，他很適合這個髮型，小明很適合這件工作等等；英文語法中並不常說某人適合某樣東西，而是要反過來說某樣東西適合某人，例如這件衣服很適合你，這個髮型很適合他，這件工作很適合小明等等；其實，中文語法中也有這樣的表達方式，只是並不常見而已。所以，正確的表達方式：

something suits someone → 主詞為東西、事物最為常見。 someone be suited for something→ 主詞是人，要把動詞suit改成形容詞suited 並加上介詞 for

Ex：你適合這件洋裝。
→This dress suits you.

Ex：你適合這個工作。
→You are suited for this job.
source from:
http://mail.scu.edu.tw/~cynthiay/3-1.htm