“It’s anyone’s guess”

“On thin ice”

In a risky or dangerous situation.

“It’s not rocket science”

It’s not very complicated.

“Get cold feet”

To become nervous and change your mind.

“Better late than never”

Doing something late is better than not doing it at all.

“Wrap one's head around something”

To understand something complicated.

“Catch someone red-handed”

To catch someone in the act of doing something wrong.

“Every cloud has a silver lining”

There is something good in every bad situation.

“Your guess is as good as mine”

I don’t know either.