  The formation of the present configuration of three hot super-Earths in the
planet system HD 40307 is a challenge to dynamical astronomers. With the two
successive period ratios both near and slightly larger than 2, the system may
have evolved from pairwise 2:1 mean motion resonances (MMRs). In this paper, we
investigate the evolutions of the period ratios of the three planets after the
primordial gas disk was depleted. Three routines are found to probably result
in the current configuration under tidal dissipation with the center star, they
are: (i) through apsidal alignment only; (ii) out of pairwise 2:1 MMRs, then
through apsidal alignment; (iii) out of the 4:2:1 Laplace Resonance (LR) , then
through apsidal alignment. All the three scenarios require the initial
eccentricities of planets $\sim0.15$, which implies a planetary scattering
history during and after the gas disk was depleted. All the three routines will
go through the apsidal alignment phase, and enter a state with near-zero
eccentricities finally. We also find some special characteristics for each
routine. If the system went through pairwise 2:1 MMRs at the beginning, the MMR
of the outer two planets would be broken first to reach the current state. As
for routine (iii), the planets would be out of the Laplace Resonance at the
place where some high-order resonances are located. At the high-order
resonances 17:8 or 32:15 of the planets c and d, the system will possibly enter
the current state as the final equilibrium.
