listEning 2 "gEologyClAss"
{$mEDiAurl}




why DoEs thE proFEssor mEntion thE spokEs oF A whEEl
A、to mAkE A point ABout thE strEAm BEDs in A trEllis pAttErn
B、to ContrAst thE FormAtion with thAt oF A rECtAngulAr onE
C、to ExplAin thE struCturE oF A rADiAl DrAinAgE systEm
D、to givE An ExAmplE oF A DEnDritiC DrAinAgE systEm