用often改为:Lucy and Lily often do their homework in the evening.
解释:Lucy and lily are going to do their homework this evening. 意思是:Lucy和Lily今晚将要做他们的作业。那么用often,也就是把将来时改为一般现在时,应该把这句话的意思改为:Lucy 和Lily经常在晚上做作业。也就是上面的答案。this evening:今天晚上——>in the evening:在晚上
Lucy and Lily often do their homeworks in the evening.
Lucy and lily often do their homework in evenings.