let us begin our class 是什么意思

let us begin our class 是什么意思 E( )is here.let us begin our class. ______everyone is here,let us begin our class Let() begin() class.A.us,us B.us,our C.we,our Let's begin our class. 选择填空一题Please ___ in class,boys and girls.Let us begin our cl （ ） everyone is here ,let us begin our class.A .Since B .For Let us begin to have our class可以不加to吗?为什么 there ( ).Let's begin our class Let,s begin ____ our class now Let,s begin to have our class now.= let,s begin having our c Let’s _____ (begin ) our class.这里填什么?