根据句意，用所给动词的适当形式填空。
1. —Who will be the host of the party?
    —As far as I know, Linda has already _____ (choose).
2. I'm sorry _____ (keep) you _____ (wait) for so long.
3. Who would you like _____ _____ (thank) for your achievements?
4. He thought they _____ (not see) each other again.
5. Thank you very much for _____ (help) me with my English.