He is an astronaut （变为复数句子）?怎么写?

He is an astronaut （变为复数句子）?怎么写? This is an apple 变为复数句子 "It is an egg"变为复数形式怎么改 将下列句子由单数变为复数形式或由复数变为单数形式 ：1.This is an eraser . 按要求写句子.1 He is an old man.（改复数形式）2 That girl is (David is) s he is an engineer.把句子改为复数形式 She is an English girl.(变为复数) where is the baseball?变为复数怎么写? He is cook noodles .变为复数形式 变为复数句子：1.There is an apple on the table. it is an orange,he is my friend 改成复数形式.还有,英文的家谱怎么写?____ tree 英语句子单数变复数He has a round face.(变为复数形式）