oom:schoolroom,classroom,bedroom
boat:sailboat,speedboat,motorboat
light:flashlight,daylight,stoplight
ache:earache,backache,headache
some:handsome,lithesome,winsome
back:halfback,running back,quarterback
这一组只有back符合条件,但是也不是完全符合,字典显示running back中间必须有个空格,是橄榄球术语,也许生活中不必要这个空格.
wood:rosewood,balsawood,fruitwood
board:cardboard blackboard backboard