they are not opened中为什么加个are?

people are not so honest as they once were.这里最后为什么加were They are books.book为什么加s -Are they happy-Not they --Are they ( ) buuks?No,they are not .--They are ( ) buuks. Who are they talking to?to什么时候加?为什么加? are the postman cold or hot ? 为什么回答是 they are not cold,they Dophina are not fish .They are mammals . The Smiths are not rich. They are ( ). not,they,the,school,are,same,in连成句子 为什么 英语中,They are watching football games.为什么game要加S They are comfortable having Chinese food中have为什么要加ing They are not new workers