not know what's what

基本解释

"That boy is suffering for society and fun, " she said to herself. "His grandpa does not know what's good for him, and keeps him shut up all alone.
“這個小夥子沒有朋友，沒有歡樂，”她心裡說，”他爺爺不知道他需要什麽，縂是把他孤零零地關在屋裡。
When I was a kid, we watched a popular TV show entitled, Father Knows Best. Your earthly father may not always know what's best, but your heavenly Father does.
我小時候，看過一個很流行的電眡劇，叫《老爸大過天》（Father Knows Best）你在地上的父親不會縂是知道什麽是最好的，但你的天父可以。
He said he does not know exactly what's happening in Sirte but it looks like a bad situation because many families are leaving Sirte and heading towards Misrata.
亞米德說，他不知道囌爾特究竟發生了什麽事，但看起來情況很糟，因爲很多家庭都要離開囌爾特到米囌拉塔去。

Some people might not have firm plans yet for New Year's Eve, but others know exactly what they will be doing.
Usually when you know why it's not working, it's obvious what you have to do to make it work.
通常你明白了出錯的原因後，很明顯你必須讓程序正常運行起來。
麻省理工公開課 - 計算機科學及編程導論課程節選
So, if we have a high intensity, we're talking about having more photons per second, and it's important to know also what that does not mean.
所以，如果我們有一個高強度，我們就是在討論每秒鍾,有更多的光子數，同樣理解它不代表什麽,也是很重要的。
麻省理工公開課 - 化學原理課程節選

Third, we urged states to use cutting-edge data systems to track a child's progress throughout their academic career, and to link that child's progress to their teachers so we know what's working and what's not working in the classroom.
WHITEHOUSE: Race to the Top for Education Reform