  Increasing observed data indicate that part of giants has abnormally high
lithium (Li) inside their surface, and their proportion is around 1%. Instead
of pursuing the feasible mechanisms for extra Li enrichment, we focus on how to
inhibit Li depletion from the main sequence (MS) phase of giants. With this in
mind, we find that convective mixing is capable of achieving this goal and
forming Li-rich giants, which is mainly attributed to the convection model with
the convective boundary defined by the Ledoux criterion. Another factor in the
formation of Li-rich giants in our convection models is related to the Li
abundances of their progenitors. If the Li abundances of the progenitors exceed
the meteoritic value (3.3 dex), then the majority of giants will be rich in Li.
This is the general pattern of stellar Li abundance evolution without factoring
in extra Li depletion. We propose that other Li depletion processes should also
be adopted in the future, as they may be the key to the 1% puzzle.
