Cr2O72-中Cr元素的化合价为（ ） A．+2 B．+3 C．+5 D．+6 发布时间：2017-05-22 20:45 │ 来源：www.tikuol.com 题型：选择题 问题： Cr2O72-中Cr元素的化合价为（ ）A．+2B．+3C．+5D．+6
题型：选择题 A transport layer protocol has several responsibilities. One is to create a process-to-process (program-to-program) communication; TCP uses port (71) to accomplish this. Another responsibility of a transport layer protocol is to create a (72) and error-control mechanism at the transport level. TCP uses a sliding (73) protocol to achieve flow control. It uses the acknowledgment packet, time-out, and retransmission to achieve (74) control. The transport layer is also responsible for providing a connection mechanism for the application program. The application program sends (75) of data to the transport layer. It is the responsibility of the transport layer at the sending station to make a connection with the receiver.A．procedureB．functionC．routeD．flow 查看答案
题型：选择题 假设VHF超外差式接收机的第一中频为10.7MHZ，在接收频率为130.975MHz的RF信号时，频率合成器提供的本振信号频率可能为（）。A.120.275MHzB.130.975MHzC.140.975MHz 查看答案