The English language has some useful rules for the learner to know. For example: that most nouns add an -s in the plural, that adverbs are formed by adding -ly to the adjective, that the usual word order is Subject-Verb-Object. However, much of English grammar cannot be predicted from general rules, especially the behaviour of individual words. The student of English has to learn case-by-case how these words work. This aspect of the English language is often called usage (word grammar).
A common usage problem for learners is predicting how certain common verbs* should be used, particularly in reported speech. For example, you can say both: I command you to go and I command that you go. But you can only say: I insist that you go; I insist you to go is wrong.
The words quite and not only also cause usage problems:
Quite: This word has two very different meanings, dependent on the adjective that it qualifies. The sentence She's quite clever means she is not very, but reasonably, fairly, rather clever.
The sentence She's quite beautiful! means she is very, very beautiful, perfectly beautiful. (To understand these different meanings you need to know that clever is a gradable adjective, and beautiful is a non-gradable adjective.)
Not only: This expression is a cohesive device used to alert the reader/listener that a second item or example is coming next (usually introduced by the words but .. also). He is not only stupid, but he is also rude and loud.
If the expression is used at the beginning of the sentence, then the subject and verb must be inverted (and, in some cases, an auxiliary added): Not only is he stupid, but he is also rude and loud. Not only did he put his pen in the electricity socket, but he also screamed at me when I tried to stop him.
Above are just a few of the countless examples of usage that can cause learners difficulty. In order to use words correctly, learners can do the following:
* These verbs are sometimes called illocutionary verbs. They are verbs of saying, not doing. Examples are: predict, apologize, deny, suggest, demand, admit, etc. Do a quiz on illocutionary verbs.