幼儿的耳咽管相对于成人而言( )、( )、位置平直,鼻咽部感染易引起( )。<img class="questionIndex" data-index="1" src="/common/images/question_button/BlankSpace1.gif"/><img class="questionIndex" data-index="2" src="/common/images/question_button/BlankSpace2.gif"/><img class="questionIndex" data-index="3" src="/common/images/question_button/BlankSpace3.gif"/>