The default behavior of switching to the shortest path tree as soon as a new source is detected on the shared tree can be disabled by setting the value in the ip pim spt-threshold command to "zero." （）

A . They establish routes that will never go down. B . The keep routing tables small. C . They require a great deal of CPU power. D . The allow connectivity to remote networks that are not in the routing table. E . They direct traffic from the Internet into corporate networks.

A . immediately after receiving the first packet on the shared tree for a given （S，G） B . after receiving over 1 kb/s traffic onthe shared tree for a given （S，G） C . 10 seconds after receiving the first packet on the shared tree for a given （S，G） D . 30 seconds after receiving the first packet on the shared tree for a given （S，G） E . after receiving over 10 kb/s traffic onthe shared tree for a given （S，G）

A .  Hosts 2， 3， and 4 will receive the broadcast.  B .  Hosts 1， 2， 3， and 4 will receive the broadcast. C .  Host 2 and the Fa0/0 interface of R1 will receive the broadcast. D .  Hosts 1， 2 and the Fa0/0 interface of R1 will receive the broadcast.  E .  Hosts 1， 2， 3， 4 and interface Fa0/0 of R1 will receive the broadcast. F .  Hosts 2， 3， 4， and interfaces Fa0/0 and Fa0/1 of R1 will receive the broadcast.

A . so B . unless C . if D . while

A . 192.168.1.254 B . 192.168.22.254 C . 192.168.33.254 D . 192.168.44.254

A . Null values are left out of the sort. B . Character values are displayed from Z to A C . Date values are displayed with the earliest value first. D . Null values are displayed last for descending sequences. E . Numeric values are displayed with the lowest values first.

A . The server's SQL mode determines how the server should behave when performing data validation check and interpreting different forms of syntax B . The server's SQL mode determines whether the server should be read-only or should accept commands such as INSERT and UPDATE C . The server's SQL mode can be changed at the session level with a SET SESSION sql_mode="new_value" command D . The server's SQL mode, when globally set on a slave server, applies to events sent from the master

A . Objects are deleted when they can no longer be accessed through any reference. B . The finalize（） method will eventually be called on every object. C . The finalize（） method will never be called more than once on an object. D . An object will not be garbage collected as long as it is possible for an active part of the program to  access it through a reference. E . The garbage collector will use a mark and sweep algorithm.

A．The directors of large firms will continue to anticipate the demand for products. B．The directors of large firms are less interested in achieving a predictable level of profit than in achieving a large profit. C．The directors of large firms will strive to reduce the costs of their products. D．Many directors of large firms believe that the government should establish the prices that will be charged for products.

A．Cortisol B．testosterone C．pituitary D．cxytocin

A．a purely instrumental matter B．a tool in the service of purpose C．a tool in the service of belief D．a public inheritance

A．Frequent physical exercise B．Alcohol abuse C．Tobacco cessation D．Unhealthy diet 此题为多项选择题。