21£®—What ______ to them?

—They appeared ______ in the accident.

A. happened; to have been injured

B. had happened; to be injured

C. happened; injured

D. have happened; to be injured

22£®Questions and exercises are given by the computer, which decides ______ to move the student ahead, review an easier level ______ give more work on the same level.

A. both; and¡¡¡¡¡¡¡¡¡¡¡¡   B. whether; or

C. not only; but                 D. either; or