Parents should be aware that communication between parents and their children is important,

________their heavy work loads. [ ]

A. but for   

 B. besides

C. because of    

D. despite

使用反推时，反推杆是否可以一直向后拉？（）

A.要等反推装置展开到位继续拉

B.使用反推时反推杆可以一直拉

C.分阶段一直拉到最大反推

D.先慢后快