有线电视系统输出端口任意频道间的载波电平差允许在（）dB之内。
参考答案：≤10
As we are _____ Table Cloth, we should be pleased if you would send us your best quotations.
A．in the market forB．on the market forC．entering the market for D．at the market for
标定盐酸常用的基准物为
A．苯甲酸钠 B．邻苯二甲酸氢钾 C．重铬酸钾D．氧化砷 E．无水碳酸钠
