[求助]GWD的一条题目,请指点,谢谢

4月7号

今天只有一题不怎么懂，太好了。呵呵

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

Answer: settlers used mud and grass to build their homes, making do without

Doubt: “making do without”不明白耶。为什么不是原句“settlers used mud and grass to build their homes, doing it without”呢？