There must to be some monkeys_____ (escape) from the zoo.

问题描述:

There must to be some monkeys_____ (escape) from the zoo.
sorry,没to

must后面多打了个to吧?
横线上填:escaping
must be doing 对于现在的肯定推测
PS. 九年级U5的练习吧...P38页-3a中有同样的句子、