---i don't think it very expensive to buy a family computer here.---really?I'll buy__next week.---i don't think it very expensive to buy a family computer here.---really?I'll buy__next week.填 one 还是 it .答案给的是one .为什么不能是it

---i don't think it very expensive to buy a family computer here.---really?I'll buy__next week.---i don't think it very expensive to buy a family computer here.---really?I'll buy__next week.填 one 还是 it .答案给的是one .为什么不能是it
---i don't think it very expensive to buy a family computer here.---really?I'll buy__next week.
---i don't think it very expensive to buy a family computer here.
---really?I'll buy__next week.
填 one 还是 it .答案给的是one .为什么不能是it

---i don't think it very expensive to buy a family computer here.---really?I'll buy__next week.---i don't think it very expensive to buy a family computer here.---really?I'll buy__next week.填 one 还是 it .答案给的是one .为什么不能是it
one 指任何一个
it 指上文提到的那一个

it强调了某一个here的computer
one只是说我会买一个（任何一个）
从对话看没有特指
用one就可以。。。
而且个人觉得one比较顺口

填one。这里是泛指电脑，所以用one。
it是指前文提到过或者特定的事物。这里不需要特指。
希望对你有帮助～～～

我准备下周买一部。。不是买它。