请解释最后一句英文的语法But I had never drawn a sheep.So I drew for him one of the two pictures I had drawn so often.It was that of the boa constrictor from the outside.注：the two pictures指the boa constrictor from the inside和the boa constrictor from the outside
问题描述：
请解释最后一句英文的语法
But I had never drawn a sheep.So I drew for him one of the two pictures I had drawn so often.It was that of the boa constrictor from the outside.
注：the two pictures指the boa constrictor from the inside和the boa constrictor from the outside
答
it was THAT of the boa constrictor..
先忽略 of the outside 之类的
that 可以指代某样东西
that of the boa constrictor..是指那幅画的某样东西