jci认证有意义吗:thousends of years ago| years应该加s吗?

thousends of years ago| years应该加s吗? We have a f____ of twenty years. NewYork has a short history of some three hundered years. shall remain effective for a period of three years Trees have grown and died for__. A.millons of year B.millons of years C.millons years选哪个?为什么? Half of the workers here are under twenty __B__ A.years old B. years of age 为什么选B Ten Years of Sexy Anumber of years ago 英语填空:Shanghai( )a small town hundreds of years ago . Now it ( )a large city. 用英语解释句子8.Our country has a hospital of 5000 years.