this is a bus.(改为否定句）

this is a bus.(改为否定句） This bus is for the thertre.改为否定句 Is this a bus （改为复数句 this is a map.(改为否定句) This is a watch.改为否定句. this is letter A.改为否定句 This is a clock改为否定句 This is a lion.改为否定句 The bus stop is near a factory.改为否定句 This is a UFO改为否定句还有This is a letter A 改为否定句 this is a bus.把它改为复数句 This is a book.(改为否定句） this is a map of china改为否定句 tHIS IS A MAP OF cHINA.改为否定句 [紧急求助]This is a ruler.改为否定句 this is a bag 改为否定句是什么 This is a fat boy. 怎么改为否定句 This is a bus.改为复数.