问题补充：
We have made great progress in the medical field, but progress we have made is not enough.
A. a; a
B. a; the
C. /; the
D. /; /
答案：
A. a; a
B. a; the
(答案→)C. /; the
D. /; /
解析：冠词题。第一空短语make progress “取得进步”；第二空progress有定语修饰特指。 我们在化学领域取得了很大进步但这进步还不够。 选C
