GBS典型的脑脊液改变是蛋白质含量增高,而细胞数正常,称为_______分离现象,为本病特点之一。蛋白质增高于起病后第_______周最明显。
参考答案:蛋白-细胞‖3
Mr. Black_____a telephone meeting when I got to his office yesterday afternoon.[ ]
A. has
B. had
C. is having
D. was having
如果有相同的电阻率的掺杂锗和硅半导体,问哪一个材料的少子浓度高,为什么?