21. His son was put in________ prison. He went to________prison to see him yesterday.
A./;/ B.the;the
C./;the D.the;/
22. All the people _______ at the meeting can only be sure of what has happened ______, but cannot be sure of something in the future.
A.eager; at times B.present; at present
C.late; from then D.absent; now and then