Do you know that the first textbooks written for teaching English as a foreign language ____ in the 16th century?
Do you think it necessary that we have all the chairs_________?
________do you think _________ the monitor of our class?
.We were about to go downstairs when the lights_________.
.Jack couldn’t answer the question_________ got the money.
—You did so much work today.You must be very tired. —No,I’m not_________tired.