流感病毒的血凝素和神经氨酸酶属于（）
A.衣壳
B.核心
C.包膜
D.刺突
E.壳粒
参考答案：D
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
某轮在有风流的水域航行，如图所示，灯塔L正横时的推算船位是（）。
A．a
B．b
C．c
D．d
