There is somebody at the door,____I go and see who it is?

There is somebody at the door,____I go and see who it is?
A Shall B Must C Will D Would
应该选A ，为什么?
能不能说的详细点？

There is somebo是什么意思? there is （ ） over there There is ,there was, there were 造句 While there is life ,there is hope. there is a hero There is considerable ...... There is _____answer. No One Is There Is there a time ?