you'd better___(keep)the fire burning in the evening

问题描述:

you'd better___(keep)the fire burning in the evening
she opened the door ___(let)the children come

1.keep
you'd better do sth 表示建议“你最好做某事”,do为动词原形
2.to let
不定式to接动词原形,表示目的"目的是"