34. --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
30. It was once called the Sea of Bamboo, but now only one fifth of the area ______ covered with bamboo, and sixty percent of other plants ______ taken the place of the bamboo.