Put the verbs into the present continuous:Listen to the birds. They (sing) .Look at that one. It (fly) high in the sky.The

Present Continuous = to be + Verb + ing

Listen to the birds. They are singing(sing+ing) .Look at that one. It is flying( fly+ing) high in the sky. The other one is playing( play+ing) with a worm. I feel happy because I am having (have+ing) a good time here in these woods.