he is very busy(writing)his papers.he is far too busy（to receive）callersbusy后面只能加doing的形式吗?那后面的空为什么是to do的形式呢?求讲解

分类: 作业答案 • 2022-01-04 12:15:11

问题描述：

he is very busy(writing)his papers.he is far too busy（to receive）callers
busy后面只能加doing的形式吗?那后面的空为什么是to do的形式呢?求讲解

答