英语单选加讲解This exercise is -----difficult-----A.so,that few of

英语单选加讲解This exercise is _____difficult_____A.so,that few of us can do B.so,that few of us can do itC.,too for anyone of us to do itB和C是都对吗too和for之间有逗号，不好意思啊，我忘记了