How to save frequent flyer miles about to expire<br>Shop through an airline portal. Almost every airline has online malls or portals where you can shop. You'll earn extra miles on your purchases, and the clock will " reset, " so you won't lose any miles because of inactivity.
frequent flyer miles are earned at a diminishing rate over time
the paragraph does not mention the rate at which you earn miles, therefore it is impossible to say frequent flyer miles are earned at a diminishing rate over time. not sure how the system missed this

( z1 earn :ARG1 ( z2 mile :mod ( z3 fly :ARG1-of ( z4 frequent ) ) ) :manner ( z5 rate :ARG1-of ( z6 diminish :mod ( z7 over-time ) ) ) )