1.是：I don't know what I should do.
2.
1）如果只是一個(gè)簡(jiǎn)單的特殊疑問(wèn)句,它要求采用倒裝結(jié)構(gòu),應(yīng)該是：
What should I do?
2）但是此句中,what should I do不是單獨(dú)的句子,而是做主句謂語(yǔ)動(dòng)詞know的賓語(yǔ)從句,而從句的結(jié)構(gòu)一律是：疑問(wèn)詞/引導(dǎo)詞 + 陳述句（句序）.
所以一定要變成：I don't know what I should do.
what就是疑問(wèn)詞/引導(dǎo)詞,而I should do才是陳述句序（即主謂賓等結(jié)構(gòu)按序排列）,should I do不是陳述句的句序.
3）再如：
簡(jiǎn)單的特殊疑問(wèn)句：How old is he?
它變成從句是：I don't know how old he is.