以下哪种情况是彩色多普勒血流显像仪质量好的主要标志() ["灰阶显像分辨率高","检出低速血流的敏感度高,抗低频噪音信号能力强","可连接外设多","功能多、性能价格比高","具备升级潜能"]
姜片虫的中间宿主是() ["扁卷螺","钉螺","中华按蚊","淡水川卷螺","水生植物"]
霍乱流行期间较次要的传染源是() ["重症病人","典型病人","轻型病人","隐性感染者","潜伏期和恢复期带菌者"]
治疗重症肌无力的药物为()。 ["免疫抑制剂","抗胆碱酯酶药","皮质类固醇","免疫球蛋白","神经保护剂"]
在进行多普勒检查时哪项不需特别关注() ["血流方向","血流信号的特征","有无血流","多普勒增益","利用彩色多普勒测量血管宽度"]
简述工程造价管理的目的。