Ответ:
- of — Ben's trying to think of a name for his new pet. (придумать)
- by — She phoned her mother by mistake. (по ошибке)
- about — Don't worry about the test. (волноваться о)
- of — It was a waste of money. (трата денег)
- at — The sailors were lost at sea. (в море)
- to — She hasn't written to me recently. (писать кому-либо)
