Fill in the blank

Here are the suggested fill-ins for the blanks:

1. language
2. vowel
3. What is the longest word in English which has only one vowel?
4. Can you give me an English word that can function as a noun, a verb, and an adjective?
5. One of the reasons why the evolution of English is open is that it has borrowed many words.
6. Nowadays, there are many varieties of English all over the world such as British English, American English, Australian English, Indian English, etc.
7. My sister's close friend works as a bilingual secretary for an insurance company. She is able to speak English and French equally well.
8. One of the basic characteristics of English is the simplicity of form. Many English words have been simplified over centuries.
9. It's not easy for adult students to improve their speaking skills when they learn English because they often find it hard to change the way they speak.
10. Adult students have more difficulties in developing speaking skills than young learners. It's more important to be able to speak clearly so that people can understand you.

Feel free to adjust any of the suggested completes based on context or preference!