Here is ( )bike my uncle sent me last week.I believe it's( )

Here is ( )bike my uncle sent me last week。I believe it's( )fantastic one 填 the a 为什么啊 原因因为my uncle sent me 是定语从句修饰the bike,属特指,所以用定冠词the。it's(a)fantastic one 属【第一次】出现,泛指,所以用冠词a