187. (32525-!-item-!-188;#058&007080) (GWD-1-Q32)
To develop more accurate population forecasts, demographers have to know a great deal more than now about the social and economic determinants of fertility. A. have to know a great deal more than now about the social and economic B. have to know a great deal more than they do now about the social and economical C. would have to know a great deal more than they do now about the social and economical D. would have to know a great deal more than they do now about the social and economic E. would have to know a great deal more than now about the social and economic key: D 这里为什么要用would呢? would在这里表示什么意思啊? |