Life in the twenty-first century is much easier than _____ A

Life in the twenty-first century is much easier than _____ A that used to be B it is used to
C it was used to D it used to be

D ,used to do即过去经常做的意思,故选D.C be used to do是被用来做什么之意
希望对你有帮助哦亲~~~