甲型流感病毒中最易发生变异的结构是()
A．衣壳抗原
B．核蛋白
C．膜蛋白
D．包膜抗原
E．核酸
参考答案：D
They _______ faces in the classroom when the teacher came in. [ ]
A. were making
B. was making
C. make
D. made
封闭式基金一般每周或更长时间公布一次基金份额资产净值。( )
