新东方补充材料315题,郁闷阿，郁闷

315

On the Great Plains, nineteenth-century settlers used mud and grass to build their homes, doing it without timber and nails.

D. settlers used mud and grass to build their homes, making do without;

为什么答案选D, 而不选A.?????

写完了帖子，再一琢磨，知道错误所在了，呵呵：doing it 里的it没有指代对象，所以错了