About 80 percent of the students in our school_____ been working on the program and about two-thirds of the work _____been finished.  

A．have; has

B．has; have,

C．have; have

D．has; has

净种就是清除在调制过程中未清除干净和混进的（）以及（），如果皮、树枝、树叶、果翅、鳞片、土块等。