选出合适的选项将短文补充完整。

When you read1 English book, you often come across new words. You may 2guess the meanings(意思) from the words you know, but when you cannot guess the meanings of new words at all, what should you do?

You have a good 3then. From him you can learn what a word means, how to pronounce(发音) a word, how to use a word, and so on. This friend can always be with you, and you can always ask4to help you. 5is this friend? It is a dictionary. You can learn important things about words from it, so you must know how to use it.