资料来源 : pyDict

交错群落

资料来源 : Webster's Revised Unabridged Dictionary (1913)

Altern \Al"tern\, a. [L. alternus, fr. alter another: cf. F.
   alterne.]
   Acting by turns; alternate. --Milton.

   {Altern base} (Trig.), a second side made base, in
      distinction from a side previously regarded as base.