Which one of these statements about connecting to the Internet is true______

A．The Internet can only be used to link computers with same operating system

B．The Internet can be used to connect computers with different ISP

C．You must have a modem to connect to the Internet

D．You must have a telephone line to connect to the Internet

东风8B型内燃机车采用的4Q2B型组合接触器主触头的数量为（）。

A、2级，每级3对触头

B、一组常开

C、一组长闭

D、2组常开