下列关于无记名股票的阐述不正确的是( )。

A．无记名股票转让相对简便
B．无记名股票安全性较差
C．无记名股票认购时可以分次缴纳出资
D．无记名股票认购时要求一次缴纳出资

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.

3（）

A．collision

B．congestion

C．drop

D．delay