Sample to learn grammar? Read a grammar book useful? In fact, grammar learned from reading. Grammar book useful of course, but it is the same, is only the dictionary from auxiliary tools. Only see a grammar book never reading, will run amok, its end and memorize new words are the same.
From reading and understanding the grammar, again with a grammar book consolidate the knowledge and understanding
Give a simple example. Function words the looks be like simple, actually usage esoteric changeable. A detailed grammar books often will record the dozens of use of the rules, as well as countless exceptions, and exception is an exception. For example: "according to article 5 of function words and regulations the third section, here the application and not a, but because some words in front, accord with the exceptions three, so here in the..." . See, so many rules and exception, if feel it, remember so many? Even if noted down the time of writing, also don't necessarily use draw.
Learn grammar, the language sense than rules important
Develop the habit of reading English. Still with the for example. Every time when reading always meet the word dozens of times, and each time can meet different situations, different sentence structures. Read more, and pay more attention to the relationship between the words, they can understand the word out natural subtle usage, can also make mistakes when writing less.
Read confused, again to explore a grammar book
At this time, a grammar book multifarious rules just come in handy. Because you know they are looking for what, also know how these grammar rules applied to the actual sentence.