diff --git a/0003/input.py b/0005/input.py
similarity index 100%
rename from 0003/input.py
rename to 0005/input.py
diff --git a/0004/if.py b/0006/if.py
similarity index 100%
rename from 0004/if.py
rename to 0006/if.py
diff --git a/0007/if-elif-else.py b/0007/if-elif-else.py
new file mode 100644
index 0000000..b4be104
--- /dev/null
+++ b/0007/if-elif-else.py
@@ -0,0 +1,47 @@
+age = 20
+
+if age < 18:
+    print("你是未成年人")
+elif age >= 18 and age < 30:
+    print("你是年轻人")
+else:
+    print("你是成年人")
+
+
+"""
+编写一个程序，根据用户输入的分数（0-100），输出 “不及格”、“及格”、“良好”、“优秀”。
+"""
+score = float(input("请输入您的分数："))
+if score < 60:
+    print(f"{score}分不及格")
+elif score == 60:
+    print(f"{score}分及格")
+elif score < 85:
+    print(f"{score}分良好")
+else:
+    print(f"{score}分优秀")
+
+
+"""
+应用：编写一个程序，根据用户输入的月份，输出对应的季节（如 “1” 对应 “冬季”）。
+"""
+
+month = int(input("请输入月份："))
+if month == 3 or month == 4 or month == 5:
+    print(f"{month}月为春季")
+elif month == 6 or month == 7 or month == 8:
+    print(f"{month}月为夏季")
+elif month == 9 or month == 10 or month == 11:
+    print(f"{month}月为秋季")
+elif month == 12 or month == 1 or month == 2:
+    print(f"{month}月为冬季")
+
+
+"""
+挑战：编写一个程序，根据用户输入的年份，判断是否为闰年（能被4整除且不能被100整除，或者能被400整除的年份为闰年）。
+"""
+year = int(input("请输入年份："))
+if (year % 4 == 0 and year % 100 != 0) or (year % 400 == 0):
+    print(f"{year}是闰年") 
+else:
+    print(f"{year}是平年")
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