问题
选择题
We all know that we ________ our carbon footprint, but I suspect that many people wouldn't be prepared to go as far as Joan Pick, a retired scientist living in south London.
A．must have reduced
B．should have reduced
C．may have reduced
D．could have reduced
答案
答案：B
B 考察情态动词。句义：我们都知道本应该减少碳，但是我怀疑很少有人能够项Joan Pick一样。Must have done表示对过去情况的肯定推测。过去一定…；should have done本应该做某事，实际上却未做。May have done或许…；表示没有太大的把握，根据句义说明B正确。