刮板链按布置方式分为中单链、中双链、()和准边双链。
参考答案:边双链
Summer is coming. The days are getting _ . [ ]
A. long and long
B. long and longer
C. longer and longer
乡镇企业()承担支农的义务。
A.可以
B.不必
C.必须
D.不能