Qhov laj thawj tseem ceeb vim li cas miv poob lawv cov plaub hau feem ntau yog vim cov plaub hau hloov raws caij nyoog. Thaum lub caij nplooj ntoos hlav thiab lub caij ntuj sov tuaj, miv yuav tsum tau tshem lawv cov plaub; Thaum lub caij nplooj zeeg thiab lub caij ntuj no tuaj, miv yuav tsum tau muab tso rau ntawm tuab fluff.
