21. One of my friends asked me to help him with his lessons this weekend, and thus __ my plan.

A. ruined              B. ruining           C. to ruin            D. ruins

22.His teacher told him that since his parents were working abroad , either his grandparents or one of his uncles ______ allowed to come to the parents’ meeting .

A. was                    B. were               C. are                 D. is