am接在I之后，is放在单数的名词或代词之后，are放在复数的名词或代词之后，否定句在be后加not,
一般疑问句将be提前。回答：Yes,
人称代词+ be./ No, 人称代词+be + not.
He is
Mr. Chen. He is not Mr. Chen. Is he Mr. Chen? Yes, he is. / No, he is not.
I am a student. I am not a student. Are you a student? Yes, I am. / No, I am not.
They are teachers. They are not teachers. Are they teachers? Yes, they are. / No, they are not.
2.名词的复数：1） 一般在名词词尾加--s，如； car----cars; apple---apples 2） 以s,x,ch,sh结尾的词，在词尾加---es，如：box---boxes; bus---buses; watch ---watches. 3） 部分国人的复数：以an结尾的单词，在词尾加—s；以结尾的单词，单复数同形。如：Chinese---Chinese, Japanese---Japanese, American---Americans Brazilian—Brazilians, Canadian---Canadians. 4)以
辅音字母+y结尾，变y为i再加es，如：family---families. 5）以fe、f结尾，变fe、f为ve再加s，如：life---lives. 6）特殊情况，如：mouse---mice； foot---feet.