update: 2md

Author: zhenda-hub

content/posts/algorithm.md

@@ -55,8 +55,8 @@ series = ['software']
 回溯
 动态规划
 滚动数组
-快慢指针
-
+双指针
+模拟: 没有“算法技巧”，就是把现实过程**翻译成代码**的每一步。一步步再现算法的逻辑、状态变化、和中间过程。
 
 
 

content/posts/english-stu.md

@@ -195,11 +195,24 @@ listen = 主动，用心去听
 | 感叹词 | Interjection | interj. | oh, wow, hey         |
 
 
-### 时态
+#### 动词的时态
 
-now perfect: still before  had past verb
-past verb
-past perfect: had past verb
+
+实际上英语真正常用的时态只有：
+
+现在 / 过去 / 将来 × 简单 + 进行 + 完成 = 9 种常用。
+
+简单时： I eat / I ate / I will eat
+进行时： I am eating / I was eating / I will be eating
+完成时： I have eaten / I had eaten / I will have eaten
+这 9 个覆盖 99% 的实际使用场景。
+
+
+| ⏰ 时间             | 🌱 核心时态（90% 用于日常）                            | 🌿 常用补充（10%）                                                   | 🪶 很少使用（可略）                          |
+| :--------------- | :------------------------------------------- | :------------------------------------------------------------- | :----------------------------------- |
+| **现在 (Present)** | ✅ 一般现在时 → I eat. <br>✅ 现在进行时 → I am eating.<br>✅ 现在完成时 → I have eaten.  |                                        | ⚪ 现在完成进行时 → I have been eating.      |
+| **过去 (Past)**    | ✅ 一般过去时 → I ate.  | ☑️ 过去完成时 → I had eaten.<br>☑️ 过去进行时 → I was eating.                                        | ⚪ 过去完成进行时 → I had been eating.       |
+| **将来 (Future)**  | ✅ 一般将来时 → I will eat.                        | ☑️ 将来进行时 → I will be eating. <br>☑️ 将来完成时 → I will have eaten. | ⚪ 将来完成进行时 → I will have been eating. |
 
 ## 句子结构