How to fix this ArrayIndex error?

I would like to fetch datas with checking id with some numbers.

int r = 0;
var ask = from y in entity.sorulars    
          where y.soru_id == questionID[r]
          select new { y.sorutipi_id };

foreach (var hold2 in ask)
{
    questionTypeID[r] = hold2.sorutipi_id;
    r++;
}

I use these codes but

"The LINQ expression node type 'ArrayIndex' is not supported in LINQ to Entities."

error appears. I guess questionID[r] is not supported in LINQ so what should I type instead of it. Thank you