The little girl couldn’t ________ the problem. She wasn’t ________ clever.
You can’t imagine that a well –behaved gentleman ______ be so rude to a lady.
— Write to me when you get home. — __________.
I was really anxious about you. You _______ home without a word.
“Did Jim come?” “I don’t know. He _______ while I was out.”
“Look at these tracks. It _______ be a wolf.” “Don’t be so sure. I think it _______ be a fox.”