I（ ）read a great deal though I d

I（ ）read a great deal though I don't have much time for books now.

used to

have used to

am used to

was used to

used to do：过去常常；be used to doing：习惯于；be used to do：被用作为，没有B，这里不可能是我被用为读书，所以应该选过去常常，不选CD。句意：虽然现在没有很多时间看书，但我以前读过很多书。