2. Seeing a word, hearing a word, saying a word and writing a word helps to make it part of your active vocabulary.
能够识别、听懂、口、笔头运用一个单词，才能说你掌握了它。
3. In terms of category of words, it can function as notional word, such as verb, pronoun, conjunction, as well as functional word, such as auxiliary word, emotional word, etc.
在词类上，它可以是实词，做动词、代词、连词等；也可以是虚词，做助词、语气词等。
4. The primary method is mouth-to-mouth breathing, in which the rescuer breathes into the victim's mouth, with pauses to allow exhalation.
最基本的方法是口对口人工呼吸法：急救者将嘴紧贴在患者嘴上，然后往患者嘴里吹气，吹完，急救者即将自己的嘴移开，使患者得以呼气。
5. The mouth bar contacts with the frontal sand bar and acidic water can easily flow into mouth bar. The feldspar in sand bodies of mouth bar is dissolved and generates secondary pores.
河口坝与前缘砂坝接触，酸性水容易进入河口坝，河口坝砂体中的长石受酸性水溶蚀，形成次生孔隙。
