_____是be kept to do还是be kept doing?

be kept to do 为什么是must be kept而不是must to be kept 是must be to do还是must be doing Our room must ___ clean.A.keep B.be kept C.to be D.kept People should ____cutting trees A be kept to cut B be kept f _____ came that his ______should be kept secret. We are kept ___ of 填to be informed ,to inform ,informing还是in 是be up to sb to do还是doing? secret should be kept...是什么意思? be accustomed to 是接doing 还是接do? be found+doing还是to do? be addicted to do还是doing?