可以通过电子邮件发送的文件类型有（ ）。
①视频文件②音频文件③图片文件④文本文件
电子邮件是—种用电子手段提供信息交换的通信方式，是互联网应用最广的服务。通过网络的电子邮件系统，用户可以以非常低廉的价格（不管发送到哪里，都只需负担网费）、非常快速的方式（几秒钟之内可以发送到世界上任何指定的目的地），与世界上任何一个角落的网络用户联系。
电子邮件内容可以是文字、图像、声音等多种形式。同时，用户可以得到大量免费的新闻、专题邮件，并实现轻松的信息搜索。
ICMP is short for Internet（ ）Message Protocol, and is an integral part of the Internet（ ）suite (commonly referred to as TCP/IP). It is a（ ）layer protocol used by network devices to diagnose network communication issues. IP is not designed to be absolutely reliable. ICMP is to provide feedback about problems in the communication environment, not to make IP（ ）.One of the most well-known and useful messages in an ICMP datagram is the Destination（ ）message which is generated for several reasons, including unable to reach a network, a host, aport, or a protocol.
ICMP is short for Internet（ ）Message Protocol, and is an integral part of the Internet（ ）suite (commonly referred to as TCP/IP). It is a（ ）layer protocol used by network devices to diagnose network communication issues. IP is not designed to be absolutely reliable. ICMP is to provide feedback about problems in the communication environment, not to make IP（ ）.One of the most well-known and useful messages in an ICMP datagram is the Destination（ ）message which is generated for several reasons, including unable to reach a network, a host, aport, or a protocol.
ICMP is short for Internet（ ）Message Protocol, and is an integral part of the Internet（ ）suite (commonly referred to as TCP/IP). It is a（ ）layer protocol used by network devices to diagnose network communication issues. IP is not designed to be absolutely reliable. ICMP is to provide feedback about problems in the communication environment, not to make IP（ ）.One of the most well-known and useful messages in an ICMP datagram is the Destination（ ）message which is generated for several reasons, including unable to reach a network, a host, aport, or a protocol.
ICMP is short for Internet（ ）Message Protocol, and is an integral part of the Internet（ ）suite (commonly referred to as TCP/IP). It is a（ ）layer protocol used by network devices to diagnose network communication issues. IP is not designed to be absolutely reliable. ICMP is to provide feedback about problems in the communication environment, not to make IP（ ）.One of the most well-known and useful messages in an ICMP datagram is the Destination（ ）message which is generated for several reasons, including unable to reach a network, a host, aport, or a protocol.
ICMP is short for Internet（ ）Message Protocol, and is an integral part of the Internet（ ）suite (commonly referred to as TCP/IP). It is a（ ）layer protocol used by network devices to diagnose network communication issues. IP is not designed to be absolutely reliable. ICMP is to provide feedback about problems in the communication environment, not to make IP（ ）.One of the most well-known and useful messages in an ICMP datagram is the Destination（ ）message which is generated for several reasons, including unable to reach a network, a host, aport, or a protocol.
电子邮件系统中，发送邮件协议为SMTP协议，使用的端口号是（ ）。
可以通过电子邮件发送的文件类型有（ ）。
①视频文件②音频文件③图片文件④文本文件
下列关于ping命令的描述中，说法错误的是（ ）。
在Windows中，执行（ ）命令可以查看域名信息。
在Windows中，要查看到目标主机Alice的路径，可使用（ ）命令。
