The stone ___ must be moved away.

What are you doing out of bed, Tom?  You are___________ to be asleep.

—This morning your mobile phone was always busy. I couldn’t ________ to you until several attempts.—Oh, I’m sorry. I was discussing the price of our products with a client over the phone.

When it ______ research into heart disease and its effects on the body, we do not have adequate substitutes for the use of animals.

Don’t get upset—I was only ______.             .