哪位高手来帮我英语句子的单复数转换啊、谢了、急、

1. these are my books.
2. they are apples.
3. look, there are red apples on the table.
4. we are students.
5. that is an orange.
希望对你有帮助~请问我提的就是复数吗、1-4是单数转复数5 本身是复数，我把它转单了