many ways have been found_small and simple machines to processlarge and complicated machine parts a by usingb to usec usingd used
问题描述：
many ways have been found_small and simple machines to process
large and complicated machine parts
a by using
b to use
c using
d used
答
how
答
B 动词不定式做定语 修饰ways 许多这样的……方法被找到
答
首先,排除c,d选项,表被动的been found不可以直接接动词 后应调整语序（to process指得到处理,来处理的意思,先省略）many ways to use small and simple machines have been found many ways by using small and sim...
答
已经找到了很多可以启动进行简易机器的方法。