diff --git a/【实践课外】3.选择结构2/7-1 选择-奇数平方和.c b/【实践课外】3.选择结构2/7-1 选择-奇数平方和.c
new file mode 100644
index 0000000..92cf6fa
--- /dev/null
+++ b/【实践课外】3.选择结构2/7-1 选择-奇数平方和.c	
@@ -0,0 +1,52 @@
+#include <stdio.h>
+
+int main() {
+    int a, b, c, d, e;
+    int ans_odd = 0, ans_even = 0;
+
+    scanf("%d %d %d %d %d", &a, &b, &c, &d, &e);
+
+    if (a % 2 == 0) {
+        ans_even += a * a;
+    } else {
+        ans_odd += a * a;
+    }
+
+    if (b % 2 == 0) {
+        ans_even += b * b;
+    } else {
+        ans_odd += b * b;
+    }
+
+    if (c % 2 == 0) {
+        ans_even += c * c;
+    } else {
+        ans_odd += c * c;
+    }
+
+    if (d % 2 == 0) {
+        ans_even += d * d;
+    } else {
+        ans_odd += d * d;
+    }
+
+    if (e % 2 == 0) {
+        ans_even += e * e;
+    } else {
+        ans_odd += e * e;
+    }
+
+    if (ans_odd == 0) {
+        printf("No Odd Number\n");
+    } else {
+        printf("%d\n", ans_odd);
+    }
+
+    if (ans_even == 0) {
+        printf("No Even Number\n");
+    } else {
+        printf("%d\n", ans_even);
+    }
+
+    return 0;
+}
diff --git a/【实践课外】3.选择结构2/7-1 选择-奇数平方和.jpg b/【实践课外】3.选择结构2/7-1 选择-奇数平方和.jpg
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diff --git a/【实践课外】3.选择结构2/7-2 选择-外卖.c b/【实践课外】3.选择结构2/7-2 选择-外卖.c
new file mode 100644
index 0000000..6c782f5
--- /dev/null
+++ b/【实践课外】3.选择结构2/7-2 选择-外卖.c	
@@ -0,0 +1,18 @@
+#include <math.h>
+#include <stdio.h>
+
+int main() {
+    double x, y;
+
+    scanf("%lf%lf", &x, &y);
+
+    if (x <= 0 && y >= 0 || x <= y && y <= 0) {
+        printf("\\^O^/\n");
+    } else if (x > y && y <= 0) {  //  类似 -0.5 -0.75 的情况
+        printf("1\n");
+    } else {
+        printf("%d\n", (int)ceil(y / x));
+    }
+
+    return 0;
+}
diff --git a/【实践课外】3.选择结构2/7-2 选择-外卖.jpg b/【实践课外】3.选择结构2/7-2 选择-外卖.jpg
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diff --git a/【实践课外】3.选择结构2/7-3 选择-糖果.c b/【实践课外】3.选择结构2/7-3 选择-糖果.c
new file mode 100644
index 0000000..17e46a8
--- /dev/null
+++ b/【实践课外】3.选择结构2/7-3 选择-糖果.c	
@@ -0,0 +1,15 @@
+#include <stdio.h>
+
+int main() {
+    int n, m;
+
+    scanf("%d%d", &n, &m);
+
+    if (n >= m + 1 && n % (m + 1) == 0) {
+        printf("Second win\n");
+    } else {
+        printf("First win\n");
+    }
+
+    return 0;
+}
diff --git a/【实践课外】3.选择结构2/7-3 选择-糖果.jpg b/【实践课外】3.选择结构2/7-3 选择-糖果.jpg
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diff --git a/【实践课外】3.选择结构2/7-4 C程序设计 实验2-2-2成绩转换（switch）.c b/【实践课外】3.选择结构2/7-4 C程序设计 实验2-2-2成绩转换（switch）.c
new file mode 100644
index 0000000..7b5e2e3
--- /dev/null
+++ b/【实践课外】3.选择结构2/7-4 C程序设计 实验2-2-2成绩转换（switch）.c	
@@ -0,0 +1,36 @@
+#include <stdio.h>
+
+int main() {
+    int score;
+
+    scanf("%d", &score);
+
+    switch (score / 10) {
+        case 10:
+        case 9:
+            printf("A\n");
+            break;
+        case 8:
+            printf("B\n");
+            break;
+        case 7:
+            printf("C\n");
+            break;
+        case 6:
+            printf("D\n");
+            break;
+        case 5:
+        case 4:
+        case 3:
+        case 2:
+        case 1:
+        case 0:
+            printf("E\n");
+            break;
+        default:
+            printf("Input error!\n");
+            break;
+    }
+
+    return 0;
+}
diff --git a/【实践课外】3.选择结构2/7-4 C程序设计 实验2-2-2成绩转换（switch）.jpg b/【实践课外】3.选择结构2/7-4 C程序设计 实验2-2-2成绩转换（switch）.jpg
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diff --git a/【实践课外】3.选择结构2/7-5 选择-我是特种兵.c b/【实践课外】3.选择结构2/7-5 选择-我是特种兵.c
new file mode 100644
index 0000000..2afcc5d
--- /dev/null
+++ b/【实践课外】3.选择结构2/7-5 选择-我是特种兵.c	
@@ -0,0 +1,19 @@
+#include <stdio.h>
+
+int main() {
+    int x1, y1, x2, y2, x3, y3;
+
+    scanf("%d%d%d%d%d%d", &x1, &y1, &x2, &y2, &x3, &y3);
+
+    int d1 = (x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2);
+    int d2 = (x1 - x3) * (x1 - x3) + (y1 - y3) * (y1 - y3);
+    int d3 = (x2 - x3) * (x2 - x3) + (y2 - y3) * (y2 - y3);
+
+    if (d1 + d2 == d3) {
+        printf("yes\n");
+    } else {
+        printf("no\n");
+    }
+
+    return 0;
+}
diff --git a/【实践课外】3.选择结构2/7-5 选择-我是特种兵.jpg b/【实践课外】3.选择结构2/7-5 选择-我是特种兵.jpg
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diff --git a/【实践课外】3.选择结构2/7-6 选择-奖学金.c b/【实践课外】3.选择结构2/7-6 选择-奖学金.c
new file mode 100644
index 0000000..364f483
--- /dev/null
+++ b/【实践课外】3.选择结构2/7-6 选择-奖学金.c	
@@ -0,0 +1,32 @@
+#include <stdio.h>
+
+int main() {
+    int id, avg_score, dis_score, is_cadre, paper_num;
+    int ans = 0;
+
+    scanf("%d%d%d%d%d", &id, &avg_score, &dis_score, &is_cadre, &paper_num);
+
+    // 院士奖学金
+    if (avg_score > 80 && paper_num >= 1) {
+        ans += 8000;
+    }
+
+    // 五四奖学金
+    if (avg_score > 85 && dis_score > 80) {
+        ans += 4000;
+    }
+
+    // 成绩优秀奖
+    if (avg_score > 90) {
+        ans += 2000;
+    }
+
+    // 班级贡献奖
+    if (dis_score > 80 && is_cadre) {
+        ans += 850;
+    }
+
+    printf("%d\n", ans);
+
+    return 0;
+}
diff --git a/【实践课外】3.选择结构2/7-6 选择-奖学金.jpg b/【实践课外】3.选择结构2/7-6 选择-奖学金.jpg
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diff --git a/【实践课外】3.选择结构2/7-7 选择-K线图.c b/【实践课外】3.选择结构2/7-7 选择-K线图.c
new file mode 100644
index 0000000..d548e6b
--- /dev/null
+++ b/【实践课外】3.选择结构2/7-7 选择-K线图.c	
@@ -0,0 +1,29 @@
+#include <stdio.h>
+
+int main() {
+    double open, high, low, close;
+
+    scanf("%lf%lf%lf%lf", &open, &high, &low, &close);
+
+    if (close < open) {
+        printf("BW-Solid");
+    } else if (close > open) {
+        printf("R-Hollow");
+    } else {
+        printf("R-Cross");
+    }
+
+    if (low < open && low < close || high > open && high > close) {
+        printf(" with ");
+
+        if (low < open && low < close && high > open && high > close) {
+            printf("Lower Shadow and Upper Shadow");
+        } else if (low < open && low < close) {
+            printf("Lower Shadow");
+        } else {  // high > open && high > close
+            printf("Upper Shadow");
+        }
+    }
+
+    return 0;
+}
diff --git a/【实践课外】3.选择结构2/7-7 选择-K线图.jpg b/【实践课外】3.选择结构2/7-7 选择-K线图.jpg
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