diff --git a/src/exercises/01.md b/src/exercises/01.md
index 94c630d3..30baeea3 100644
--- a/src/exercises/01.md
+++ b/src/exercises/01.md
@@ -157,7 +157,7 @@ function useReducer<r extends Reducer<any, any>>(
 ): [ReducerState<r>, Dispatch<reduceraction<r>>]
 ```
 
-`useReducer` is pretty versatile. They key takeaway here is that while
+`useReducer` is pretty versatile. The key takeaway here is that while
 conventions are useful, understanding the API and its capabilities is more
 important.
 
</div><div class="naked_ctrl">
<form action="/index.cgi/larger-text" method="get" name="gate">
<p><a href="http://altstyle.alfasado.net">AltStyle</a> によって変換されたページ <a href="https://patch-diff.githubusercontent.com/raw/epicweb-dev/advanced-react-apis/pull/11.diff">(-&gt;オリジナル)</a>
/ <label>アドレス: <input type="text" name="naked_post_url" value="https://patch-diff.githubusercontent.com/raw/epicweb-dev/advanced-react-apis/pull/11.diff" size="22" /></label> <label>モード: <select name="naked_post_mode">
<option value="default">デフォルト</option>
<option value="speech">音声ブラウザ</option>
<option value="ruby">ルビ付き</option>
<option value="contrast">配色反転</option>
<option value="larger-text" selected="selected">文字拡大</option>
<option value="mobile">モバイル</option>
</select>
<input type="submit" value="表示" />
</p>
</form>
</div>