Eyespots,themostrudimentaryeyes,arefoundinprotozoan原生动物flagellates鞭毛虫,flatworms扁形虫,andsegmentedworms片段蠕虫.

The megaphone(microphone) makes the voice sound louder because it points sound waves in one direction and keeps them from spreading out in all directions.

One of the greatest breakthroughs for professional women came in 1973 when the field of banking opened up for them.

Although the Carbon 14 method of dating old objects is not foolproof , it is the best method available at present

Solidgeometryhasenabledastronomerstocalculatethepositionsoftheheavenlybodiesrelativetooneanother.