射流紧缩，缩脉

缩脉；流颈

venae contractae───静脉收缩

land contract───[经]土地合同；土地契约

land contracts───[经]土地合同；土地契约

general contractor───[经]总承包人；建筑公司

in contrast───与此相反；比较起来

noncontract───非合同

to contract───签订合同

social contracts───社会契约（统治者与被统治者订定的详列权利义务的契约，等于social社会契约论；compact）；民约论

rescind a contract───撤销合同

Objective: To explore the roles of color Doppler vena contracta in the evaluation of mitral regurgitation grading.───目的：探讨彩色多普勒过返流口宽度在估测二尖瓣返流程度中的作用。

objective is to explore the roles of color Doppler vena contracta in the evaluation of mitral regurgitation grading.───目的是探讨彩色多普勒静脉收缩术在评估二尖瓣反流分级中的作用。