读澳大利亚气候分布图，回答下列问题．

     A woman is having some trouble(患病) with her eyes, so she goes to see the doctor. He is a new doctor and doesn’t know her, so he asks some questions and one of them is, “How old are you?”

     The woman says, “I don’t know, doctor, but let me think about it.” She thinks for a few minutes and then says, “Yes, I know now, doctor! When I marry(结婚), I am eighteen years old, and my husband is thirty. Now my husband is sixty. And that is twice(两倍) thirty. So I am twice eighteen. That’s thirty-six, isn’t it?”

能作为监测空气污染程度的指示植物（　　）

秦始皇平六国，隋炀帝富有四海，既骄且逸，一朝而败，吾亦何得自骄也？

言念于此，不觉惕焉震惧。

吴兢——《贞观政要》

材料中的“吾”是(   )