Translate the following sentence into English.
那位老人的子女不明白，从市场买菜更便宜，他为什么还要费大劲自己去种菜。(take the trouble to)
【正确答案】：
THE OLD MAN'S CHILDREN DID NOT UNDERSTAND WHY HE TOOK THE TROUBLE TO GROW HIS OWN VEGETABLES BECAUSE IT WAS CHEAPER TO BUY THEM FROM THE MARKET.
【题目解析】：
费大劲take the trouble to；种菜grow vegetables。