AO—Ah—AhB—Bt—C BAh—AB—Bk—Ck CAh—E—Bt—C DAh—AhB—Bsq—C
A沼澤土 B草甸土 C風沙土 D水稻土
A.SiO2 B.CaCO3 C.Fe2O3 D.Al2O3