() exercise at least twice a week can help you ()A.do ,to stay healthy B.doing ,stay healthC.do,stay healthy D.doing ,to stay healthy选哪个?说明一下理由,

问题描述:

() exercise at least twice a week can help you ()
A.do ,to stay healthy B.doing ,stay health
C.do,stay healthy D.doing ,to stay healthy
选哪个?说明一下理由,