为什么是there being no classes yesterday,we paid a visit to the Great wall而不是there was no classes yesterday,we paid a visit to the Great wall
问题描述：
为什么是there being no classes yesterday,we paid a visit to the Great wall
而不是there was no classes yesterday,we paid a visit to the Great wall
答
这个是独立主格的现象,逗号不能同时连接2个句子,一整个句子的主语只能有一个,所以前面的be动词要接ing的形式,否则一句话里面有2个主语了,就像这句话是一样的道理：
It being Sunday,we can play football outside home.
若是将逗号改成and的话就可以直接用be动词了,这样就是一个主语,两个谓语动词都是用来修饰这一个主语的.