请问这句话有语法上活时态上的错误吗?
Attheceremonyofyourschool's100thanniversary,weshouldalsocelebratetheachievementthatchinahasgainedinthepast20years.200millionpersonshavegetridofpoverty;theyearlypercapitaeconomicgrowthratehasreached7percentto8percent;averagelifeexpectancyhasheightened10years.