【题目】He was so ________ thought that he didn't see the pole on the road.
A.buried in
B.careful with
C.busy with
D.serious about

【答案】A
【解析】句意：他太专心于思考了，以至于没看到公路上的柱子。be buried in”埋头于，专心于“；be careful with”当心，小心“；be busy with”忙于“；be serious about”对……认真的“。故只有A项符合句意。