Are they mice?改成单数句

Are they mice?改成单数句 They are old monkeys?改成单数句 are they ruler 改成单数句 they are on sofa 改成单数句子 they are改成第三人称单数形式 They are my books.改成单数 they are改成第三人称单数形式 they are chinese boys改成单数 they are women docters.（改成单数句） 格式是（ ）is（ ）（ ）（ ） Those are old libraries.改成单数句 把下列句子改成单数句或复数句1.This is a tiger.2.Those are eggs.3.Is it a bottle?4.Are these mice?5.There is a sheep on the hill. Whose teachers are these They are ours改成单数形式 把They are apples.改为单数句 Are they students?（改为单数句） What colour are they?改为单数句 They are our friends变单数句 They are old insects单数句 Are they bookcase 怎样改为单数句?