“An uphill battle”

“An old hand”

A person with a lot of experience in something.

“Keep an eye on”

To watch or monitor carefully.

“On thin ice”

In a risky or dangerous situation.

“When pigs fly”

Something that will never happen.

“Kill two birds with one stone”

To achieve two goals with one action.

“Raining cats and dogs”

Raining very heavily.

“A picture is worth a thousand words”

An image can express more than words.

“Every cloud has a silver lining”

There is something good in every bad situation.