Sure, here are the correct forms of the given words to complete the sentences:

1. My friend, Jane has a big **collection** of dolls. (collect)
2. She wrote an **invitation** letter to ask me to join her English club last week. (invite)
3. My school organized many outdoor **activities** for students last year. (act)
4. They provide all the **safety** equipment for workers in this building. (safe)
5. People said that watching films was **exciting**. (excite)