采用国际标准是指将国际标准的内容，经过分析研究和试验验证，（）为我国标准（包括国家标准、行业标准、地方标准和企业标准。下同），并按我国标准审批发布程序审批发布。

A typical application of this (71) is ADSL. It is emerging as the technology for home-and small-office Internet connectivity. It provides either 1.5 Mb/s～8 Mb/s from the network to the user and 64 kb/s～512 kb/s in the reverse direction depending on the distance, 12000 or 18000 feet. The different speed for each direction gives it the (72) label. ADSL is designed to take advantage of the fact that video-on demand, telecommuting, and Internet access traffic are inherently asymmetrical. The user (73) a brief message up to the network and receives a ton of data coming back, either a movie or a piece of data download. Under such a scenario, low-speed traffic to the network is just fine. ADSL .delivers high (74) where you need it and only uses a single copper pair. Through multiplexing, it also reserves (75) of the bandwidth for POTS.

A．2 kHz

B．4 kHz

C．16 kHz

D．64kHz