diff --git a/docs/10.md b/docs/10.md
index e5db4216338cf93ccf5c2534693a2f82ed6e283c..509e4144fa6c905d4c9bc65a0ad066a69420565c 100644
--- a/docs/10.md
+++ b/docs/10.md
@@ -200,9 +200,11 @@ $$
 $$
 
 $$
-= 2\mathbb{E} [(\nabla_{\theta} \log \pi_{\theta}(\tau))^2 b] - 2\mathbb{E} [(\nabla_{\theta} \log \pi_{\theta}(\tau))^2 r(tau)] = 0，
+= 2\mathbb{E} [(\nabla_{\theta} \log \pi_{\theta}(\tau))^2 b] - 2\mathbb{E} [(\nabla_{\theta} \log \pi_{\theta}(\tau))^2 r(\tau)] = 0，
 $$
 
 $$
-b = \frac{\mathbb{E} [(\nabla_{\theta} \log \pi_{\theta}(\tau))^2 r(tau)]}{\mathbb{E} [(\nabla_{\theta} \log \pi_{\theta}(\tau))^2]}。
-$$
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+b = \frac{\mathbb{E} [(\nabla_{\theta} \log \pi_{\theta}(\tau))^2 r(\tau)]}{\mathbb{E} [(\nabla_{\theta} \log \pi_{\theta}(\tau))^2]}。
+$$
+
+## 3. 离线策略策略梯度（Off Policy Policy Gradient）
\ No newline at end of file