diff --git a/basic/21-aave-uni-loan/contracts/interfaces/IAToken.sol b/basic/21-aave-uni-loan/contracts/interfaces/IAToken.sol
index ff31f42ad..e9e42347b 100644
--- a/basic/21-aave-uni-loan/contracts/interfaces/IAToken.sol
+++ b/basic/21-aave-uni-loan/contracts/interfaces/IAToken.sol
@@ -26,7 +26,7 @@ interface IAToken is IERC20, IScaledBalanceToken, IInitializableAToken {
    * @param onBehalfOf The address of the user that will receive the minted aTokens
    * @param amount The amount of tokens getting minted
    * @param index The next liquidity index of the reserve
-   * @return `true` if the the previous balance of the user was 0
+   * @return `true` if the previous balance of the user was 0
    */
   function mint(
     address caller,
diff --git a/basic/23-erc865-and-erc875/contracts/erc404/ERC404.sol b/basic/23-erc865-and-erc875/contracts/erc404/ERC404.sol
index 6dd345cf0..54aa6973b 100644
--- a/basic/23-erc865-and-erc875/contracts/erc404/ERC404.sol
+++ b/basic/23-erc865-and-erc875/contracts/erc404/ERC404.sol
@@ -249,7 +249,7 @@ abstract contract ERC404 is Ownable {
             _owned[from].pop();
             // update index for the moved id
             _ownedIndex[updatedId] = _ownedIndex[amountOrId];
-            // push token to to owned
+            // push token to owned
             _owned[to].push(amountOrId);
             // update index for to owned
             _ownedIndex[amountOrId] = _owned[to].length - 1;
diff --git a/defi/Uniswap-V3/contractGuide/UniswapV3Pool.md b/defi/Uniswap-V3/contractGuide/UniswapV3Pool.md
index 966b19d97..070e2967a 100644
--- a/defi/Uniswap-V3/contractGuide/UniswapV3Pool.md
+++ b/defi/Uniswap-V3/contractGuide/UniswapV3Pool.md
@@ -263,7 +263,7 @@ struct StepComputations {
     // sqrt(price) for the next tick (1/0)
     // 目标价格(根号)
     uint160 sqrtPriceNextX96;
-    // how much is being swapped in in this step
+    // how much is being swapped in this step
     // 当前步交易了多少输入token
     uint256 amountIn;
     // how much is being swapped out