One theory is that the ________ has been present in humans for a very long time.
举一反三
- He has been an ______ (拍卖师) for a long time.
- I have known her for a long time. / She........................ to me for a long time. A: has known B: has been known C: is known
- 18. How long has Mr. Smith been working in the present office? For
- America is a young country, but it has been a spoiled country for such a long time.
- He………ill for a long time. A: has had B: has been C: is D: were