Several years has passed since we started our middle school life.这里为什么是has passed?several years不是复数形式吗,为什么不是用have passed

Several years has passed since we started our middle school life.这里为什么是has passed?several years不是复数形式吗,为什么不是用have passed several years ago He__China for several years.A has been to B has come to C has been in D came to helen has been studying piano for several years and she still___a,has b,does c,has been d,did It has been several years since he lived here.怎么翻译? He has been （ ） for several years括号中填died 还是dead She has been in China for several years.She() be a big girl now. She has been a teacherfor several years(用work as转换) For several years this group has tried to get help for bike riders. She has kept()English for several years A.practising saying B.practising speaking C. I haven’t seen your father for several years.Where has he gone --oh,he ___for three years. Mr. Jack __China for several years. A. has beenMr. Jack __China for several years. A. has been to B. has come to C.has been in D. came to in several years翻译中文 有关the past several years witnessed the phenomenon that ……时态问题请问是the past several years witnessed the phenomenon that还是the past several years have witnessed the phenomenon that 抑或the past several years has witnessed the p Alice has been in China for several years.She___be a big girl now.A.needB.canC.mayD.must For several years this group (has been trying) to get the city government to help bicycle riders.为什么括号中用has been trying,而不是has tried? Mr.White works as a journalist at present,but he ___ in a high school for several years.has worked 和 worked 到底填哪个?明明有时间状语 for several years呀! Our school has changed greatly in the past several years.There ___ ___greatl changes in the past several years in our school.改同义句.这个非延续动词是怎么变成延续性动词的？