细菌外毒素
A．主要由革兰阴性菌产生
B．可产生Shwartzman现象
C．易引起弥散性血管内凝血
D．对组织器官有特殊的亲嗜性
E．耐热
参考答案：D
圆锥形筒子随着直径增大，大端的圆周速度由（）到（）。
Everybody in the little town knew my first teacher, so we had no _____ finding his home.
A．difficulties in
B．difficulty with
C．difficulty
D．difficulty to
