Update Amount.md

🔰 Grammar/Amount.md

@@ -54,3 +54,15 @@ Like くらい, it describes an approximate amount. It focuses on a limit being
 
 > [!info] Example
 > {地下鉄|ちかてつ}を{乗|の}るために、{死|し}ぬ==程=={走|はし}った。
+
+## 一度に（いちどに）
+
+all at once
+
+https://jlptsensei.com/learn-japanese-grammar/%e4%b8%80%e5%ba%a6%e3%81%ab-ichido-ni-meaning/
+
+## ずつ
+
+apiece; each; at a time
+
+https://jlptsensei.com/learn-japanese-grammar/jlpt-n3-grammar-%e3%81%9a%e3%81%a4-zutsu-meaning/