People in many parts of the world are living longer lives now than people ____ in the past.
a) did
b) were
c) lived
d) had been
答案是a
想请教题目里，than之前的部分，动词是？ are living? lives?
承上题，如果动词是 are living，did和were怎么选？
谢谢

than people ( in many parts of the world ) lived inthe past . lived 和前面动词一样，所以用did 代替