The Internet has greatly changed the way people communicate. But some teachers think the changes are not all for the better. Eleanor Johnson, an English professor, thinks that text messaging has made students believe that it is far more acceptable than it actually is to just make terrible spelling and grammatical errors. And she says her students over the past several years have increasingly used less formal English in their writing. Words and phrases like "guy" and "you know" now appear in research papers. Professor Johnson supposes there is a strong relationship between the rise of informal online communication and an increase in writing mistakes. But she says there may not be much scientific information, at least not yet. David Crystal, a British linguist , says the actively changing nature of the Internet makes it difficult to keep up-to-date in studying its effects. But he believes its influence on language is small. The main effect of the Internet on language is the way it has added to the expressive richness of language, providing language with a new set of communicative tools that haven't existed in the past. Erin Jansen is founder of NetLingo.com, an online dictionary of the Internet and text messaging terms. She says the new technology has not changed existing language but has greatly added to its vocabulary. Basically it's freedom of expression. And what about those teachers who find these new kinds of mistakes in spelling and grammar in their students' work? What is her message to them? Erin Jansen said, "I am always on the students' side and won't get angry or upset about that. If it's helping the kids write more or communicate more, that's great. That's what teachers and educators want--to get kids communicating." But Erin Jansen and David Crystal agree with Eleanor Johnson on at least one thing. Teachers need to make sure students understand the uses and rules of language. The author wants to tell us that   _  .
different opinions on informal expressions exist what language is now used on the Internet informal expressions are popular among teachers why the Internet is welcomed by all students