be anyone's guess idiom
谁也不知道，谁也拿不准
If a piece of information is anyone's guess, no one knows it.
"So what's going to happen now?" "That's anyone's guess." “那现在又会发生甚么呢？”“那谁知道。”
Which of these websites will be successful is anyone's guess.
It's anyone's guess what effect these measures will have on our kids.
As for his speech last week, it's anyone's guess what it was supposed to mean.
He initially bought the painting for £3,000, but it's anyone's guess what it's worth now.