be to be done可以改成must be done

问题描述:

be to be done可以改成must be done
all goverment loans are to br repaid可不可以改成 all goverment loans must be repaid

应该不行吧 因为be to do表示将来的动作 而must没有突出“将”而是必须 我觉得应该不行