A professor said the rise of the BRICS countries(金砖国家) is a/an _______ of the end of the world in the control of the USA. A. barrier B. process C. aspect D. symptom
--Have you ever heard of an American president called Chester A.Arthur?
--No, and he is not mentioned in my history book at all. He seems ______________.
A. to have been completely forgotten B. having completely forgotten
C. to have completely forgotten D. completely forgetting