"class begin"还是"classes begin"?到底应该用哪个呢?

是class is begin还是class begin 是Class begin.还是Class begins.还是Classes begin.为什么? 是class starts 还是class begin 是before class begin 还是before class is begin class begin还是classes begin?到底应该用哪个呢? 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? Begin the class when dose the class begin? Let's begin our class. class begin at 8:00 Let's begin our class是哪种句子结构?还是主谓宾? Mike sometimes talks to others in class.(同意句) Mike sometimes ( ) ( )others in clas Let's _____our class.begin beginsLet's _____our class.begin begins to begin when does the class begin?怎么回答 What about _____(begin) our class class ______(begin)at eight o'clock. we must stop ------(talk)when class begin