What he enjoys _____ great and interesting.—Yes, but it’s dangerous.
Some scientists think that it may take ______ years to make robots look like people, and do the same things as us.
Look at the boy running on the ground. Is it Davis?—It ______ be him. I saw him go to the teacher’s office just now.
Tom _______ his English book in the classroom last Friday.
How many birds can you see in the trees?—I can see birds in them.