diff --git a/advanced_expert/vulnerabilities/README.md b/advanced_expert/vulnerabilities/README.md
index 9865058..220a097 100644
--- a/advanced_expert/vulnerabilities/README.md
+++ b/advanced_expert/vulnerabilities/README.md
@@ -7,12 +7,12 @@
 
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-* `tx.origin` needs to bere placed by `msg.sender`, otherwise any contract you call can act on your behalf.
+* `tx.origin` needs to be replaced by `msg.sender`, otherwise any contract you call can act on your behalf.
 * inline assembly should be used only in rare cases.
-* unclear semantics: `now` is alias for `block.timestamp` not current time; use of low level `call`, `callcode`, `delegatecall` should be avoided whenever possible; use `transfer` whenever failure of ether transfer should rollnack the whole transaction.
+* unclear semantics: `now` is alias for `block.timestamp` not current time; use of low level `call`, `callcode`, `delegatecall` should be avoided whenever possible; use `transfer` whenever failure of ether transfer should rollback the whole transaction.
 * beware of caller contracts: `selfdestruct` can block calling contracts unexpectedly.
 * invocation of local functions via `this`: never use `this` to call functions in the same contract, it only consumes more gas than normal call.
-* transferring Ether in a for/while/do-while loop should be avoid due to the block gas limit.
+* transferring Ether in a for/while/do-while loop should be avoided due to the block gas limit.
 * erc20 `decimals` should have `uint8` as return type.
 
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