What does the idiom 'Once in a blue moon' mean?

What does the idiom 'Bite the bullet' mean?

What does the idiom 'Break the ice' mean?

What does the idiom 'A blessing in disguise' mean?

What does the idiom 'Hit the nail on the head' mean?

What does the idiom 'Burn the midnight oil' mean?

Choose the correctly corrected sentence: 'She don't know the answer.'

Government by the people is called:

Choose the correctly corrected sentence: 'He is working here since 2018.'

A person who speaks many languages is called:

Choose the correctly corrected sentence: 'Between you and I, this is wrong.'