My brother joined the League _________ March 24,1990.He _____a League member for six yearson,has become .on,has been in,has been in,has become

Question

My brother joined the League _________ March 24,1990.He _____a League member for six years
on,has become .on,has been in,has been in,has become

Answer 1

on,has been.
表示具体的某一天,前面介词要用on,表示年,月,四季,世纪,前面用in；
后面有for表示一段时间,要用完成时,且要用表示状态或持续性的动词.所以不能用has become.