The old lady is       seriously ill        we can’t tell her about the death of his son. 

There are two small rooms in the house, _____ serves as a kitchen

．— I wonder if you _______ a picnic tomorrow.— Yes. But if it ______, we’ll visit the museum instead.

David can speak idiomatic American English and yet, _____ English, he doesn't know it at all. 

_______ is known to everybody that the moon travels round the earth once every month.