Fix typo of "舌" (#551)

* Replace "舍背" with "舌背"

* Replace "舍尾" with "舌尾"

* Replace "舍末" with "舌末"

* Replace "舍" with "舌"

1000-hours/sounds-of-american-english/1.4-articulators.md

@@ -10,7 +10,7 @@ Despite speaking different languages, humans share the same structure of brain a
 
 <video controls width="720"> <source src="/videos/speech-form-brain-signals.mp4" type="video/mp4"></source>Your browser does not support the video tag. </video>
 
-我们用**嘴**说话…… 更详细地讲，我们说话的时候动用的器官实际上很多，包括但不限于：**下巴**（*lower jaw*）、**嘴唇**（*lips*）、**牙齿**（*teeth*）、**龈脊**（*alveolar ridge*）、**舌尖**（*tongue tip*）、**舍背**（*tongue roof*）、**舌尾**（*back of tongue*）、**软腭**（*soft palate*）、**咽**（*pharynx*）、**喉**（*larynx*）、**声带**（*vocal cords*）等等。
+我们用**嘴**说话…… 更详细地讲，我们说话的时候动用的器官实际上很多，包括但不限于：**下巴**（*lower jaw*）、**嘴唇**（*lips*）、**牙齿**（*teeth*）、**龈脊**（*alveolar ridge*）、**舌尖**（*tongue tip*）、**舌背**（*tongue roof*）、**舌尾**（*back of tongue*）、**软腭**（*soft palate*）、**咽**（*pharynx*）、**喉**（*larynx*）、**声带**（*vocal cords*）等等。
 
 ![Speech Tract (zh-CN)](/images/articulators-cn.svg)
 

1000-hours/sounds-of-american-english/2.1.5-ə.md

@@ -12,7 +12,7 @@ Beginners tend to overdo it and add a <span class="pho">r</span> whenever they e
 
 The rhotacized <span class="pho">ɚ</span> and <span class="pho">ɝː</span> sounds, can be produced in two different ways. Most beginners instinctively curl their tongue tip to produce this sound, as it's generally the only method they're familiar with.
 
-由于这个音发声时的舌头动作是别人看不见的，所以，人们在学这个发音的时候，无法猜到第二种方式：舍尾部分抬起来，使舌的两侧接触到后牙。舌尾的中心部分较低，空气通过这个凹槽产生声音。
+由于这个音发声时的舌头动作是别人看不见的，所以，人们在学这个发音的时候，无法猜到第二种方式：舌尾部分抬起来，使舌的两侧接触到后牙。舌尾的中心部分较低，空气通过这个凹槽产生声音。
 
 ![articulator-tongue-tip-ɚ](/images/articulator-tongue-tip-ɚ.svg)
 

1000-hours/sounds-of-american-english/2.2.10-tʃdʒ.md

@@ -1,6 +1,6 @@
 # 2.2.10. <span class="pho">tʃ/dʒ</span>
 
-<span class="pho">ʃ/ʒ</span> 发声时舌尖贴近但没有接触到龈脊，<span class="pho">tʃ/dʒ</span> 则需要舌尖贴到龈脊，和 <span class="pho">t/d</span> 一样；但，无论是 <span class="pho">ʃ/ʒ</span> 还是 <span class="pho">tʃ/dʒ</span> 发声时舌背都抬得较高，舍尾抵到后牙。
+<span class="pho">ʃ/ʒ</span> 发声时舌尖贴近但没有接触到龈脊，<span class="pho">tʃ/dʒ</span> 则需要舌尖贴到龈脊，和 <span class="pho">t/d</span> 一样；但，无论是 <span class="pho">ʃ/ʒ</span> 还是 <span class="pho">tʃ/dʒ</span> 发声时舌背都抬得较高，舌尾抵到后牙。
 
 When pronouncing <span class="pho">ʃ/ʒ</span>, the tip of your tongue should be close to, but not touching, the alveolar ridge. For <span class="pho">tʃ/dʒ</span>, however, you need to touch the alveolar ridge with your tongue tip, same as when pronouncing <span class="pho">t/d</span>. However, when pronouncing either the sounds <span class="pho">ʃ/ʒ</span> or <span class="pho">tʃ/dʒ</span>, the tongue roof should arch higher in the mouth, with the back of it touching back teeth.
 

1000-hours/sounds-of-american-english/2.2.4-kg.md

@@ -4,7 +4,7 @@
 
 Thankfully, these two sounds exist in almost every language. Otherwise, learning them could prove quite challenging.
 
-首先，这两个音需要舍背后部抬起来顶住软腭而后开始发音。这个动作在口腔深处，所以无法直接看到。绝大多数人其实并不知道自己具体是怎么发出这两个声音的，也没有人能想起来自己小时候是如何学会的。
+首先，这两个音需要舌背后部抬起来顶住软腭而后开始发音。这个动作在口腔深处，所以无法直接看到。绝大多数人其实并不知道自己具体是怎么发出这两个声音的，也没有人能想起来自己小时候是如何学会的。
 
 Firstly, to pronounce these two sounds, the back part of the tongue must be raised and pressed against the *soft palate*. This action takes place deep in the mouth, so it's not something we can see directly. In fact, most people don't even know exactly how they produce these sounds, nor can anyone recall how they learned to make them as children.