Cov tub ntxhais kawm xyoo tsis yog tsuas yog lub sijhawm ntawm kev nkag siab ntawm kev paub txog science, tab sis kuj yog lub sijhawm ntawm kev sib deev. Yog li cov tub ntxhais kawm no es tsis txhob dhuav cov lus qhuab qhia tau paub txog kev sib deev ntawm qhov ncauj thiab qhov quav hauv tsev.
Lub tshuab kev sib deev yuav ua rau ib tug bitch tawm ntawm ib tug ntxhais. Nws zoo li tsob ntoo birch, ib txwm ntog thiab tos kom nws cov kua txiv licked. Thiab tus ntxhais no lub slit yog txhua yam ntub thiab txaus siab - leej twg tuaj yeem siv tam sim no.