I am younger then eighteen years old呢一句點解?

I am under eighteen years old. 才合英文的文法。
中文口語是『我未夠18歲！』
估計 I am younger then eighteen years old 這句的來由是 Chinglish 的傑作。
亦即是全句用中文作思考主導，用僅認識的英文寫成句子。

2007-05-26 00:17:33 補充：
這樣的冇頭冇尾的句子來發問，經常令我們摸不清前文後理，結果是和原意相去甚遠。

2007-05-26 00:18:33 補充：
then 是 than 的typing mistake

I am younger then eighteen years old呢一句點解?
大致上對方估你年歲時你會答: I am younger then eighteen years old (我還未到十八歲), 對, 沒錯.

但較正宗的同義答法:
I am almost eighteen years old.

The grammar of the sentence itself is incorrect. Did you read it somewhere or make it up yourself?

The correct grammar of the sentence should be either:
I am under eighteen years old.
or
I look younger than eighteen years old.

But then again, without knowing the whole story/conversation, it's hard to tell the real meaning of your sentence.

then ? or "than"

我未夠18歲