But the difficulty is that by the time children reach school age, there are so many other influences that it is almost i

But the difficulty is that by the time children reach school age, there are so many other influences that it is almost impossible to tell whether girls are worse at science and maths, or whether they've been brought up to think of these subjects as
boys' terrttory.
请帮忙分析一下句子结构!详细点!中英文双语更好!谢谢!