在现代，除了汽车，人们使用的最多的四个轮子的东西是什么？

这种东西男女老少人人可用，对经济条件没什么要求，没有任何使用门槛，不需要任何驾驶技术，这是什么呢？

Today there are twenty to twenty-five million shopping cart is presently one of the most often used items on four wheels, second only to the automobile. Indeed, almost everybody will spend a part of his or her life behind a shopping cart. They will, in a lifetime, push it many miles.

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