题目内容：

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

优质解答

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