請參考以下JavaScript代碼：var arr = [30, 40, 10, 50, 20];var fun = function(n) {  console.log("Before Promise => n: " + n);  return new Promise(resolve => {    console.log("After Promise => n: " + n);    setTimeout(() => {      console.log("Promise Resolved => n: " + n);      resolve(0);    }, n * 30);  });}arr.reduce((p, v) => p.then(fun(v)), Promise.resolve(0));1.如果我錯了請糾正我，Array.reduce()將上面的內容減少為以下Promise鏈：Promise.resolve(0).then(fun(30)).then(fun(40)).then(fun(10)).then(fun(50)).then(fun(20)).2.為什么輸出不是如下：Promise Resolved => n: 30Promise Resolved => n: 40Promise Resolved => n: 10Promise Resolved => n: 50Promise Resolved => n: 203.n*30如果我用固定時間更改，為什么輸出如上500？