如果直线a∥b，且直线c⊥a，则直线c与b的位置关系（ ）（填“平行”或“垂直”）．
垂直
混合喂养
Though great efforts have been ___ on their study , Annie still can’t make any improvements , which
makes her parents greatly ______ . [ ]
A. made ; disappointed
B. done ; disappointing
C. taken ; disappointed
D. given ;disappointing
