单选题 Riding on the swings (秋千) and playing with the ducks in the pond was our children's greatest pleasure when we took them to the park.
A. playing
B. was
C. children's
D. them

【正确答案】 B
【答案解析】主语是两个并列的动名词短语，所以谓语用复数。改was为were。