They were ________ busy ________ with each other ________ the time．

too; to talk; to forget

too; talking; to forget

so; to talk; that we forget

so; talking; that we forgot

They were ________ busy ________ with each other ________ the time．

too; to talk; to forget

too; talking; to forget

so; to talk; that they forgot

so; talking; that they forgot