Mom spends 50 yuan (in) buying fruit every week.—— in 可以省略
Mom spends 50 yuan on fruit every week.
It costs Mom 50 yuan to buy fruit every week.
I don't have enough money to buy this car.
This car is not cheap enough for me to buy.
This car is too expensive for me to buy.
I can't afford to buy this car.
Mike and Jim don't make fun of people any more now.
Mike and Jim don't play tricks on people any longer now.