现在进行时是buying，例如：
1.We're considering buying a new car.我们在考虑买一辆新车。
2.We priced various models before buying this one.我们比较了多种型号的价格以后才买了这一款。
3.Now is a good time to buy a house.现在买房子正是时候。
4.We're buying a new TV with the money.我们要用这笔钱买一台新电视机。
