题目内容：
For years, doctors________________millions of patients' lives with the help of microscopes.
A． have saved B． are saving
C． will save
D． were saving
参考答案：
答案解析：
单选题：For years, doctors________________millions of patients' live
- 题目分类：英语三级A级
- 题目类型：单选题
- 查看权限：VIP
B． are saving
C． will save
D． were saving