diff --git a/5_nn/3-softmax_ce.ipynb b/5_nn/3-softmax_ce.ipynb
index fe99c61..76a294e 100644
--- a/5_nn/3-softmax_ce.ipynb
+++ b/5_nn/3-softmax_ce.ipynb
@@ -263,6 +263,7 @@
     "## 参考资料\n",
     "\n",
     "* [一文详解Softmax函数](https://zhuanlan.zhihu.com/p/105722023)\n",
+    "* [损失函数：交叉熵详解](https://zhuanlan.zhihu.com/p/115277553)\n",
     "* [交叉熵代价函数（作用及公式推导）](https://blog.csdn.net/u014313009/article/details/51043064)\n",
     "* [手打例子一步一步带你看懂softmax函数以及相关求导过程](https://www.jianshu.com/p/ffa51250ba2e)\n",
     "* [简单易懂的softmax交叉熵损失函数求导](https://www.jianshu.com/p/c02a1fbffad6)"
diff --git a/6_pytorch/1-tensor.ipynb b/6_pytorch/1-tensor.ipynb
index 896558a..d52c4f3 100644
--- a/6_pytorch/1-tensor.ipynb
+++ b/6_pytorch/1-tensor.ipynb
@@ -42,7 +42,9 @@
   {
    "cell_type": "code",
    "execution_count": 2,
-   "metadata": {},
+   "metadata": {
+    "collapsed": true
+   },
    "outputs": [],
    "source": [
     "import torch\n",
@@ -52,7 +54,9 @@
   {
    "cell_type": "code",
    "execution_count": 3,
-   "metadata": {},
+   "metadata": {
+    "collapsed": true
+   },
    "outputs": [],
    "source": [
     "# 创建一个 numpy ndarray\n",
@@ -69,7 +73,9 @@
   {
    "cell_type": "code",
    "execution_count": 9,
-   "metadata": {},
+   "metadata": {
+    "collapsed": true
+   },
    "outputs": [],
    "source": [
     "pytorch_tensor1 = torch.tensor(numpy_tensor)\n",
@@ -100,7 +106,9 @@
   {
    "cell_type": "code",
    "execution_count": 5,
-   "metadata": {},
+   "metadata": {
+    "collapsed": true
+   },
    "outputs": [],
    "source": [
     "# 如果 pytorch tensor 在 cpu 上\n",
@@ -129,7 +137,9 @@
   {
    "cell_type": "code",
    "execution_count": 7,
-   "metadata": {},
+   "metadata": {
+    "collapsed": true
+   },
    "outputs": [],
    "source": [
     "# 第一种方式是定义 cuda 数据类型\n",
@@ -160,7 +170,9 @@
   {
    "cell_type": "code",
    "execution_count": 8,
-   "metadata": {},
+   "metadata": {
+    "collapsed": true
+   },
    "outputs": [],
    "source": [
     "cpu_tensor = gpu_tensor.cpu()"
@@ -716,7 +728,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.7.9"
+   "version": "3.5.4"
   }
  },
  "nbformat": 4,
diff --git a/6_pytorch/2-autograd.ipynb b/6_pytorch/2-autograd.ipynb
index 644bd57..c93f799 100644
--- a/6_pytorch/2-autograd.ipynb
+++ b/6_pytorch/2-autograd.ipynb
@@ -119,7 +119,9 @@
   {
    "cell_type": "code",
    "execution_count": 4,
-   "metadata": {},
+   "metadata": {
+    "collapsed": true
+   },
    "outputs": [],
    "source": [
     "z = torch.mean(torch.matmul(w, x) + b) # torch.matmul 是做矩阵乘法\n",
@@ -275,7 +277,9 @@
   {
    "cell_type": "code",
    "execution_count": 8,
-   "metadata": {},
+   "metadata": {
+    "collapsed": true
+   },
    "outputs": [],
    "source": [
     "n.backward(torch.ones_like(n)) # 将 (w0, w1) 取成 (1, 1)"
@@ -349,7 +353,9 @@
   {
    "cell_type": "code",
    "execution_count": 18,
-   "metadata": {},
+   "metadata": {
+    "collapsed": true
+   },
    "outputs": [],
    "source": [
     "y.backward(retain_graph=True) # 设置 retain_graph 为 True 来保留计算图"
@@ -375,7 +381,9 @@
   {
    "cell_type": "code",
    "execution_count": 20,
-   "metadata": {},
+   "metadata": {
+    "collapsed": true
+   },
    "outputs": [],
    "source": [
     "y.backward() # 再做一次自动求导，这次不保留计算图"
@@ -455,7 +463,9 @@
   {
    "cell_type": "code",
    "execution_count": 10,
-   "metadata": {},
+   "metadata": {
+    "collapsed": true
+   },
    "outputs": [],
    "source": [
     "x = torch.tensor([2, 3], dtype=torch.float, requires_grad=True)\n",
@@ -553,7 +563,7 @@
  ],
  "metadata": {
   "kernelspec": {
-   "display_name": "Python 3 (ipykernel)",
+   "display_name": "Python 3",
    "language": "python",
    "name": "python3"
   },
@@ -567,7 +577,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.9.7"
+   "version": "3.5.4"
   }
  },
  "nbformat": 4,
diff --git a/6_pytorch/3-linear-regression.ipynb b/6_pytorch/3-linear-regression.ipynb
index 2db4de0..c1ad752 100644
--- a/6_pytorch/3-linear-regression.ipynb
+++ b/6_pytorch/3-linear-regression.ipynb
@@ -151,7 +151,9 @@
   {
    "cell_type": "code",
    "execution_count": 3,
-   "metadata": {},
+   "metadata": {
+    "collapsed": true
+   },
    "outputs": [],
    "source": [
     "# 转换成 Tensor\n",
@@ -166,7 +168,9 @@
   {
    "cell_type": "code",
    "execution_count": 4,
-   "metadata": {},
+   "metadata": {
+    "collapsed": true
+   },
    "outputs": [],
    "source": [
     "# 构建线性回归模型\n",
@@ -180,7 +184,9 @@
   {
    "cell_type": "code",
    "execution_count": 5,
-   "metadata": {},
+   "metadata": {
+    "collapsed": true
+   },
    "outputs": [],
    "source": [
     "y_ = linear_model(x_train)"
@@ -275,7 +281,9 @@
   {
    "cell_type": "code",
    "execution_count": 8,
-   "metadata": {},
+   "metadata": {
+    "collapsed": true
+   },
    "outputs": [],
    "source": [
     "# 自动求导\n",
@@ -305,7 +313,9 @@
   {
    "cell_type": "code",
    "execution_count": 10,
-   "metadata": {},
+   "metadata": {
+    "collapsed": true
+   },
    "outputs": [],
    "source": [
     "# 更新一次参数\n",
@@ -542,7 +552,9 @@
   {
    "cell_type": "code",
    "execution_count": 17,
-   "metadata": {},
+   "metadata": {
+    "collapsed": true
+   },
    "outputs": [],
    "source": [
     "# 构建数据 x 和 y\n",
@@ -582,7 +594,9 @@
   {
    "cell_type": "code",
    "execution_count": 19,
-   "metadata": {},
+   "metadata": {
+    "collapsed": true
+   },
    "outputs": [],
    "source": [
     "# 定义参数\n",
@@ -670,7 +684,9 @@
   {
    "cell_type": "code",
    "execution_count": 22,
-   "metadata": {},
+   "metadata": {
+    "collapsed": true
+   },
    "outputs": [],
    "source": [
     "# 自动求导\n",
@@ -702,7 +718,9 @@
   {
    "cell_type": "code",
    "execution_count": 24,
-   "metadata": {},
+   "metadata": {
+    "collapsed": true
+   },
    "outputs": [],
    "source": [
     "# 更新一下参数\n",
@@ -853,7 +871,7 @@
  ],
  "metadata": {
   "kernelspec": {
-   "display_name": "Python 3 (ipykernel)",
+   "display_name": "Python 3",
    "language": "python",
    "name": "python3"
   },
@@ -867,7 +885,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.9.7"
+   "version": "3.5.4"
   }
  },
  "nbformat": 4,
diff --git a/6_pytorch/optimizer/6_6-adam.ipynb b/6_pytorch/optimizer/6_6-adam.ipynb
index 48ff972..15cb6df 100644
--- a/6_pytorch/optimizer/6_6-adam.ipynb
+++ b/6_pytorch/optimizer/6_6-adam.ipynb
@@ -47,7 +47,9 @@
   {
    "cell_type": "code",
    "execution_count": 1,
-   "metadata": {},
+   "metadata": {
+    "collapsed": true
+   },
    "outputs": [],
    "source": [
     "def adam(parameters, vs, sqrs, lr, t, beta1=0.9, beta2=0.999):\n",
@@ -63,7 +65,9 @@
   {
    "cell_type": "code",
    "execution_count": 2,
-   "metadata": {},
+   "metadata": {
+    "collapsed": true
+   },
    "outputs": [],
    "source": [
     "import numpy as np\n",
@@ -267,7 +271,7 @@
  ],
  "metadata": {
   "kernelspec": {
-   "display_name": "Python 3 (ipykernel)",
+   "display_name": "Python 3",
    "language": "python",
    "name": "python3"
   },
@@ -281,7 +285,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.9.7"
+   "version": "3.5.4"
   }
  },
  "nbformat": 4,
diff --git a/7_deep_learning/1_CNN/2-vgg.ipynb b/7_deep_learning/1_CNN/2-vgg.ipynb
index e0db203..b21bfde 100644
--- a/7_deep_learning/1_CNN/2-vgg.ipynb
+++ b/7_deep_learning/1_CNN/2-vgg.ipynb
@@ -462,7 +462,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.7.9"
+   "version": "3.5.4"
   }
  },
  "nbformat": 4,
diff --git a/7_deep_learning/1_CNN/CNN_Introduction.pptx b/7_deep_learning/1_CNN/CNN_Introduction.pptx
index 843c650..52e5bcc 100644
Binary files a/7_deep_learning/1_CNN/CNN_Introduction.pptx and b/7_deep_learning/1_CNN/CNN_Introduction.pptx differ