IV. Combine each pair of sentences to make a complete sentence, using a suitable relative pronoun. 21. The simplest definition of language is that “language is the means of communication”. It is widely accepted. 22. There are about one billion people. They use English as the lingua franca of international communication. 23. Differences between languages can cause some problems to learners. Differences between languages are explained in course books. 24. A great number of people speak English as a foreign language. Their native language is not English. 25. English has been regarded as a lingua franca. It enjoys more universality than any other language.