禁做骨髓穿刺的疾病是（）

A.粒细胞缺乏症

B.恶性组织细胞病

C.全血细胞减少患者

D.血友病

E.白血病

In low-speed network, it is usually adequate to wait for congestion to occur and then react to it by telling the source of packets to slow down. In high-speed networks, this approach often works poorly, because in the (1) between sending the notification and notification arriving at the source, thousands of additional (2) may arrive. In ATM network, a major tool for preventing (3) is (4) control. When a host wants a new virtual (5) ,it must describe the traffic to be offered and the service expected.

4（）

A．flow

B．admission

C．traffic

D．time