Then make sentences. We use this/these/that/those in the singular and this/these/that/those

We use this in the singular and these in the plural. We use that in the singular and those in the plural.

This is a pen. These are pens.

This is a flower. These are flowers.

This is a window. These are windows.

This is a dog. These are dogs.

This is a cat. These are cats.

This is a rat. These are rats.

This is a green tree. These are green trees.

This is a high building. These are high buildings.

That is a mouse. Those are mice.

That is a yellow leaf. Those are yellow leaves.

That is a good singer.   Those are good singers.