InthenortheasternUnitedStates,itrainsintermittently间歇地throughoutthespring.
A、steadilySome sea urchins海胆 have venomous (toxin) spines
Thefirstpaperwasmadefromthebarkofthemulberrytree.
Eyespots, the most rudimentary eyes, are found in protozoan原生动物 flagellates 鞭毛虫 , flatworms 扁形虫 , and segmented worms片段 蠕虫 .
Comets are still regarded with awe by some people.
The Native American interpreter Sacajawea was a valuable member of the Lewis and dark expedition in 1805.
