at/in/on ,use which one?

答案應該是 on。

即：

I bought a lot of souvenirs for my friends and parents on Lamma Island too.

例句可見：

1. Cambridge Dictionary Online (http://dictionary.cambridge.org/dictionary/british/island)

- They live on the large Japanese island of Hokkaido.

2. Yahoo! 字典 (http://hk.dictionary.yahoo.com/dictionary?p=island)

- He lived on a small island off the shore.

在牛津高階英漢雙語字典中查「islander」也可找到類似的例句：

- ... person living on a small island ...


2010-07-22 23:21:03 補充：
It should be "on", according to the above mentioned dictionaries, which are supposed to be authoritative and reliable.

It is fine to add "from some shops", but not necessary.

By the way, "sovenirs" is a wrong spelling. The correct spelling should be "souvenirs".

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http://acjosni.w15.dnssky.net/yahoo.com.hk/hk/auction/178987536

你的問題的問題在於個too字。因為一句中只有一件事，「你買了記念品(手信)...」那麼too是甚麼意思呢？用上too句子中必須要有兩樣事件。不要誤會你給朋友跟給父母是兩樣嘢，句子文法是一件事向兩對象而已，並不構成too。

另外你的答案是at/in/on，但其實選擇上也錯了，因為似乎你是說那些記念品是在lamma island買的，但如用at/in/on在句子中是表示你的記念品是送給住在lamma island的朋友和父母。就會用"on" xx island.

其實你在補充中已經hit中正確寫法，只要減去too便是一句好句：
I bought a lot of souvenirs for my friends and parents from Lamma Island.
或
I bought a lot of souvenirs from Lamma Island for my friends and parents.會比較正規。
[留意souvenir串錯字]

正確的prespostion是from(由...買來的記念品)

當然如上文解釋at/in/on這些preposition也會產生不同意思的，所以要注意preposition的關連的是甚麼
at a "specific location"
in a "place/area/region"
on a "platform"

Chiu Winnie：
應用 I bought a lot of sovenirs for my friends and parents at Lamma Island
too.纔對, 用 in 和 on 是錯的。

2010-07-22 21:57:19 補充：
The preposition' in' is used with names of countries and big towns like'in America, in Paris'
, ' at' is more often used with relatively smaller places like ' at an island, at a village' ,
whereas 'on' is often used in speaking of things at rest like' on a chair',etc.