Rewrite sentences without changing the meaning

I wish I hadn’t accepted the invitation to her birthday party.

Each sentence has a mistake. Find it by choosing the letter A, B, C or D.

What kind of activities is this organization involved to?

Each sentence has a mistake. Find it by choosing the letter A, B, C or D.

What international organizations would you like to work for: WWF, WHO or the UN?

Each sentence has a mistake. Find it by choosing the letter A, B, C or D.

WWF, who name stands for World Wide Fund, was established in 1961.

Each sentence has a mistake. Find it by choosing the letter A, B, C or D.

We fill on the form to register for the environmental campaign.

Choose the letter A, B, C or D to complete the sentences with given words

The team captain/ for / the referee / blamed / their loss / in the last / game.

Each sentence has a mistake. Find it by choosing the letter A, B, C or D.

If I work for WHO, I can help the sick people to get round.