【单选题】Training for a marathon requires careful preparation and steady, gradual increases in the length of the runs. ___1___, buy the best-fitting, best-built running shoes you can find. No one can say which...
A.
After six days
B.
For a good marathon runner
C.
Before you begin your training
D.
With each day, increase the distance by a half mile
E.
If they still feel good, you can begin running in them
F.
Time spent for preparation raises the quality of training
G.
Now you are ready to figure out a goal of improving distance and time