diff --git "a/\347\254\254\344\272\214\346\234\237\350\256\255\347\273\203\350\220\245/1\347\217\255/1\347\217\255_7/1\347\217\255_7-\347\254\254\345\233\233\345\221\250/.keep" "b/\347\254\254\344\272\214\346\234\237\350\256\255\347\273\203\350\220\245/1\347\217\255/1\347\217\255_7/1\347\217\255_7-\347\254\254\345\233\233\345\221\250/.keep"
new file mode 100644
index 0000000000000000000000000000000000000000..e69de29bb2d1d6434b8b29ae775ad8c2e48c5391
diff --git "a/\347\254\254\344\272\214\346\234\237\350\256\255\347\273\203\350\220\245/1\347\217\255/1\347\217\255_7/1\347\217\255_7-\347\254\254\345\233\233\345\221\250/lesson4-1.py" "b/\347\254\254\344\272\214\346\234\237\350\256\255\347\273\203\350\220\245/1\347\217\255/1\347\217\255_7/1\347\217\255_7-\347\254\254\345\233\233\345\221\250/lesson4-1.py"
new file mode 100644
index 0000000000000000000000000000000000000000..d9b5f57e265f929f4f5ace24eb248709eef381c5
--- /dev/null
+++ "b/\347\254\254\344\272\214\346\234\237\350\256\255\347\273\203\350\220\245/1\347\217\255/1\347\217\255_7/1\347\217\255_7-\347\254\254\345\233\233\345\221\250/lesson4-1.py"
@@ -0,0 +1,33 @@
+
+#  datetime、str、time 之间的转换
+#
+import datetime
+now = datetime.datetime.now()
+
+time_str = now.strftime("%Y-%m-%d %H:%M:%S")
+str_time = datetime.datetime.strptime(time_str,"%Y-%m-%d %H:%M:%S")
+
+time_smp = now.timestamp()
+smp_time = datetime.datetime.fromtimestamp(time_smp)
+
+
+
+# 封装一个函数get_date(day_delta), 如果传入的是-1 , 输出就是字符串日期
+import datetime
+def get_date(day_delta):
+    now = datetime.datetime.now()
+    day_delta = int(input('请输入代表数字：（当前日期请输入【-1】）'))
+    if day_delta == '-1':
+        day_delta = now + datetime.timedelta(days=-1)
+        day_delta
+    return print('请重新输入：')
+
+get_date(day_delta=-1)
+
+
+
+
+
+
+
+