> 1. How would you call a function on a third party contract B, on behalf of the sender, through your contract A, guaranteeing no reverts?
## **解析：**
题目意思就是如何通过合约A代表发送者调用合约B的函数，答案很简单咯，就是[delegatecall](https://solidity-by-e...
## where is external call
```solidity
msg.sender.call(hex"")
```
```js
UniswapExchangeLiks(exchange).sync();
validate the address
```
```js
ERC20like(token).decimals();
```
## can the call be hooked
is there a way for an attacker to gain control of your execution
```
contra...