It ________ quite correct that happiness comes from thinking about things in a positive way. [ ]

A. has turned out  

B. has been turned out

C. is turning out  

D. is turned out

在轻型吊杆装置中，吊货索采用滑车组对（）。

A.千斤索张力有影响

B.吊杆轴向压力无影响

C.吊杆压力，千斤索张力都无影响

D.吊杆轴向压力有影响，千斤索张力无影响