As soon as I saw the computer, I showed great interest in it.

(Alternatively: The moment / Immediately / Once / When I saw the computer, I showed great interest in it.)

________ I saw the computer, I showed great interest in it.

A At first

B For the first time

C Until

D The first time

 

D 

 解析

The first time是固定搭配，只能这样用，放句首后面接一个句子，意思是我一看见（什么什么）。At first是个副词短语，不能连句子，要打个逗号。 For the first time是放句末的一个补充。Until意思不对。