具有化生血液作用的气是（）

A.正气

B.元气

C.宗气

D.营气

E.卫气

— How do you study ______ a test?      

— I study ______ working ______ a group. [ ]

A. for, in,with

B. for, by, at

C. for, by, with

D. of, in, by