正常工作条件下的薄壁小孔口与圆柱形外管嘴，直径ｄ相等，作用水头Ｈ相等，则孔口流量和孔口收缩断面流速与管嘴流量和管嘴出口流速的关系是（　　）。

A、<img width="44" height="24" src="http://admintk.100xuexi.com/UpLoadImage/2016-10-26/df66fb91-f927-4012-a310-c3ada39f0c89.png" />，<img width="52" height="24" src="http://admintk.100xuexi.com/UpLoadImage/2016-10-26/66fda421-404b-4014-82e6-a60fa06290e0.png" />

B、<img width="44" height="24" src="http://admintk.100xuexi.com/UpLoadImage/2016-10-26/df66fb91-f927-4012-a310-c3ada39f0c89.png" />，<img width="52" height="24" src="http://admintk.100xuexi.com/UpLoadImage/2016-10-26/f1c0311b-6653-4583-b688-be099480a891.png" />

C、<img width="44" height="24" src="http://admintk.100xuexi.com/UpLoadImage/2016-10-26/ff6b91c8-21f9-47f5-95b2-286f9f83d7cd.png" />，<img width="52" height="24" src="http://admintk.100xuexi.com/UpLoadImage/2016-10-26/66fda421-404b-4014-82e6-a60fa06290e0.png" />

D、<img width="44" height="24" src="http://admintk.100xuexi.com/UpLoadImage/2016-10-26/ff6b91c8-21f9-47f5-95b2-286f9f83d7cd.png" />，<img width="52" height="24" src="http://admintk.100xuexi.com/UpLoadImage/2016-10-26/f1c0311b-6653-4583-b688-be099480a891.png" />