Do you know Tom kept ___ by his parents until he was fifteen?

Do you know Tom kept ___ by his parents until he was fifteen?
oh,he's the laziest boy I’ve ever heard.
答案是dressed 想问keep dressed是个什么用法 为什么可以直接用被动 而不要be动词
另一个也是跟被动有关
What colour will make you feel relaxed?--- I hear that the room makes you calm down if___
A.painting in blue B.painting blue C.painting blue Dpainted blue
if后可以跟不完整的句子吗 还有就是被动怎么也没有be动词