Sure, let's analyze the stress patterns of each word to determine which one has a different main stress pattern from the others:

1. A. **model** (ˈmɒd.əl) - stress on the first syllable
B. **tomorrow** (təˈmɒr.oʊ) - stress on the second syllable
C. **theater** (ˈθiː.ə.tər) - stress on the first syllable
D. **market** (ˈmɑː.kɪt) - stress on the first syllable
**Answer: B. tomorrow**

2. A. **activity** (ækˈtɪv.ɪ.ti) - stress on the second syllable
B. **skating** (ˈskeɪ.tɪŋ) - stress on the first syllable
C. **bowling** (ˈboʊ.lɪŋ) - stress on the first syllable
D. **surfing** (ˈsɜː.fɪŋ) - stress on the first syllable
**Answer: A. activity**

3. A. **invite** (ɪnˈvaɪt) - stress on the second syllable
B. **danger** (ˈdeɪn.dʒər) - stress on the first syllable
C. **excited** (ɪkˈsaɪ.tɪd) - stress on the second syllable
D. **provide** (prəˈvaɪd) - stress on the second syllable
**Answer: B. danger**

4. A. **mountain** (ˈmaʊn.tɪn) - stress on the first syllable
B. **boring** (ˈbɔː.rɪŋ) - stress on the first syllable
C. **interesting** (ˈɪn.trə.stɪŋ) - stress on the first syllable
D. **enjoy** (ɪnˈdʒɔɪ) - stress on the second syllable
**Answer: D. enjoy**

5. A. **extreme** (ɪkˈstriːm) - stress on the second syllable
B. **tonight** (təˈnaɪt) - stress on the second syllable
C. **opposite** (ˈɒp.ə.zɪt) - stress on the first syllable
D. **equipment** (ɪˈkwɪp.mənt) - stress on the second syllable
**Answer: C. opposite**

So, the answers are:
1. B. tomorrow
2. A. activity
3. B. danger
4. D. enjoy
5. C. opposite