以下哪种等高线是基本等高线（）。
A.计曲线
B.首曲线
C.间曲线
D.助曲线
参考答案：B
—Your father was worried about something this morning, why?
—He wanted to know _____.[ ]
A. where he could mend the television
B. why he mend the television
C. that he mended the television
D. how did he mend the television
______类网络数据传输负荷重，对网络数据的实时性要求高。
A．MIS/OA/Web类应用 B．FTP/CAD类应用C．多媒体数据流文件 D．模拟信号
