英语compound word问题题目是3个单词对1个单词 且都能组成3个新的单词类似：base；basket；snow+ball=baseball；basketball；snowball我现在需要school；class；bedsail；speed；motor flash；day；stopear；back；headhand；lithe；winhalf；running；quarterrose；balsa；fruitcard；black；back上面这些组加什么才能组成新的单词呢.（注意,必须是同时满足三个的单词,ing；er之类的不行.必须是单词）

schooltime; classtime; bedtime
sailboat;speedboat;motorboat
flashlight; daylight; stoplight;
earache;backache;headache;
handsome;lithesome;winsome
halfback;runningback; quarterback
rosewood;balsewood;fruitwood
cardcardboard;blackboard;backboard

room:schoolroom,classroom,bedroomboat:sailboat,speedboat,motorboatlight:flashlight,daylight,stoplightache:earache,backache,headachesome:handsome,lithesome,winsomeback:halfback,running back,quarterback...