是class is begin还是class begin

是class is begin还是class begin 是before class begin 还是before class is begin 是Class begin.还是Class begins.还是Classes begin.为什么? 是class starts 还是class begin 是用Class begin 还是Class begins好像class begin是习惯用语,但应该用三单! 老师喊上课,下课 ,用英语怎么说~class begin ,class begins,class beginning,class is begin?class is over,class over?到底是什么?我想问over 在这是什么词性?名词,形容词,还是副词?begin 在这又是什么词性? class begin还是classes begin?到底应该用哪个呢? （ ）_______ at 8：00 in the morning.A.The classes begins B.Class begin C.Class begins1,He has lunch quickly.= He has _________ _________ lunch.（ ）2._______ at 8：00 in the morning.A.The classes begins B.Class begin C.Class begins D.Begin cla The first class ( )at 8:00 amA：begin B:is begin C：begins D:is beginning E( ) is here.Let us begin with our class. __________ everone is here,let's begin our class. E( )is here.let us begin our class. class 由被动的吗?比如说上课 是 class begins 还是 class is begun? what time（ ）the guitar class（ ） a.is begin b.does begin c.do ,to begin begin是动词还是名词 begin是及物动词还是不及物动词? Begin the class 是what time is class over还是what time is the class over请说明理由