21．− Can you _________ all the money that I should pay?
− Very sorry. Please wait a minute, madam.
A. add B. add to C. add up D. add up to
22. He must be leaving our village because he is __________.
A. making up B. packing up C. setting up D. getting up
23. My son has changed so much that I could hardly __________ his voice on the phone.
A. recognize B. realize C. hear D. find
