be careful _______(knock) down when you walk across the road.

问题描述:

be careful _______(knock) down when you walk across the road.
如题,打算写 not to be knocked

没错!
这里指“横马路时注意别被车撞倒
由于表被动,同时带否定意思,故用否定的不定式的被动式
be careful not to do sth 小心别.