内容介绍：冠词练习 1冠词填空：在下列句中空白处填入适当冠词，不需用冠词处划×。 1．There is _______ picture of _______ elephant on _______ wall． 2．This is _______ useful book．I\'ve read it for _______ hour． 3． _______ elephant is much heavier tha