Here are the answers for the words or phrases that are opposite in meaning to the underlined parts in each sentence:

1. **alone** - B. together
2. **begin** - A. end
3. **big** - D. small
4. **cool** - B. hot (correct answer is not provided in choices, but it should be an opposite; however, the closest choice is B. cold)
5. **clean** - A. dirty

If you have any further questions or need more help, feel free to ask!