Lizzie bought herself a mountain bike.

莉齐给自己买了一辆山地自行车。

In 1981 it launched the first mass-produced mountain bike.

在1981年，首款大批量生产的山地车投放市场。

I want to buy a mountain bike.

我想买一辆山地车。

But I don't have a mountain bike.

可是我没有越野自行车。

It is a mountain bike, three years old, red.

是一辆红色山地车，用过三年了。