Directions: In this section, you will hear 8 short conversations and 2 long conversations. At the end of each conversation, one or more questions will be asked about what was said. Both the conversation and the questions will be spoken only once. After each question there will be a pause. During the pause, you must read the four choices marked A, B, C and D, and decide which is the best answer.
A. He turned suddenly and ran into a tree.
B. He was hit by a fallen box from a truck.
C. He drove too fast and crashed into a truck.
D. He was trying to overtake the truck ahead of him.
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Directions: In this section, you will hear 8 short conversations and 2 long conversations. At the end of each conversation, one or more questions will be asked about what was said. Both the conversation and the questions will be spoken only once. After each question there will be a pause. During the pause, you must read the four choices marked A, B, C and D, and decide which is the best answer.
A. Check their computer files.
B. Make some computations.
C. Study a computer program.
D. Assemble a computer.
虚拟局域网(Virtual LAN)是与地理位置无关的局域网的一个广播域,由一个工作站发送的广播信息帧只能发送到具有相同虚拟网号的其他站点,可以形象地认为,VLAN是在物理局域网中划分出的独立通信区域。在以交换机为核心的交换式局域网络中,VLAN技术应用广泛,其优势在于控制了网络上的广播风暴,增加了网络的安全性,利于采用集中化的管理控制。其中,基于端口的VLAN划分方式较为常见,通过将网络设备的端口划归不同的VLAN以实现广播帧的隔离。 以下为Cisco以太网交换机Catalyst 2924(ws-c2924xlA,拥有24个10/100M自适应端口)的VLAN划分命令,请解释【1】-【3】处标有下划线部分的配置命令的含义。(“//”后为注释内容) switch>en //进入特权执行状态 switch # config term //进入通用配置状态 switch(config)# interface vlan 1 //配置vlan 1(ID为1的vlan) 【1】(此处有两条下划线) switch(config-if)# ip address 202.112.111.23.255.255.255.0 switch(config-if)# management switch(config-if)# exit //退出对vlan的配置状态 . . . switch(config)# interface fa0/1 //配置第一个模块的第二个端口 【2】(此处有两条下划线) switch(config-if)# switchport mode access switch(config-if)# switchport acess vlan switch(conflg-if)# exit //退出对端口的配置状态 . . . swltch(config)# interface fa0/2 //配置第一个模块的第三个端口 【3】(此处有两条下划线) switch(config-if)# switchport mode multi switch(config-if)# switchport multi vlan add 2,3 SWltch(config-if)# exit //退出对端口的配置状态
Directions: In this section, you will hear 8 short conversations and 2 long conversations. At the end of each conversation, one or more questions will be asked about what was said. Both the conversation and the questions will be spoken only once. After each question there will be a pause. During the pause, you must read the four choices marked A, B, C and D, and decide which is the best answer.
A. He was pleased to get the medal.
B. He used to be a firefighter.
C. He was very courageous.
D. He was accused of causing a fire.
Directions: In this section, you will hear 8 short conversations and 2 long conversations. At the end of each conversation, one or more questions will be asked about what was said. Both the conversation and the questions will be spoken only once. After each question there will be a pause. During the pause, you must read the four choices marked A, B, C and D, and decide which is the best answer.
A. The digital TV system will offer different programs.
B. He is eager to see what the new system is like.
C. He thinks it unrealistic to have 500 channels.
D. The new TV system may not provide anything better.