水系
模拟量转换为数字量由模数转换器进行，称做 ["A．B／D转换","B．A／D转换","C．D／B转换","D．A／B转换","E．A／C转换"]
MSCT的层厚最小可达 ["A．5mm","B．2mm","C．3mm","D．4mm","E．0．5mm"]
IP板的类型通常有 ["A．标准","B．高分辨率型","C．减影型","D．多体层摄影型","E．以上都是"]
CR经X线照射后在IP板上存留的是 ["A．模拟信号","B．数字信号","C．黑白影像","D．彩色影像","E．电信号"]
河流的成因。
