diff --git a/common/index.tsx b/common/index.tsx
index 5b4563e..229ff08 100644
--- a/common/index.tsx
+++ b/common/index.tsx
@@ -1,14 +1,17 @@
+const API_PREFIX = "/duty";
+
 export const get = async (url: string) => {
-  const resp = await fetch(url);
+  const resp = await fetch(`${API_PREFIX}${url}`);
   const json = await resp.json();
   return json;
 };
+
 export const post = async (
   url: string,
   json: any,
   headers: Record<string, string> = {}
 ) => {
-  const resp = await fetch(url, {
+  const resp = await fetch(`${API_PREFIX}${url}`, {
     method: "POST",
     headers: { "Content-Type": "application/json", ...headers },
     body: JSON.stringify(json),
diff --git a/components/Timetable.tsx b/components/Timetable.tsx
index 1db3379..f93d232 100644
--- a/components/Timetable.tsx
+++ b/components/Timetable.tsx
@@ -79,10 +79,13 @@ const Timetable = ({
 
     if (disableNetwork) return;
 
+    // Immediately revert the checkbox state
+    target.checked = !target.checked;
+
     // post request
     const json = await post("/api/record", {
       name: target.name,
-      checked: target.checked,
+      checked: !target.checked,
       user,
     });
     if (json.error !== undefined) {
@@ -100,6 +103,7 @@ const Timetable = ({
 
   const handleInput = (event: React.ChangeEvent<HTMLInputElement>): boolean => {
     const { target } = event;
+
     // validate
     if (target?.children[0]?.tagName !== "TABLE") {
       console.log("not a table");
@@ -202,7 +206,7 @@ const Timetable = ({
     }
     const occupied: string[] = json.occupied;
     const myselect: string[] = json.myselect;
-    console.log(json);
+    // console.log(json);
     for (const index in indexToElement) {
       if (occupied.includes(index)) {
         indexToElement[index].style.display = "none";
@@ -226,7 +230,7 @@ const Timetable = ({
 
     const interval = setInterval(() => {
       refresh();
-    }, 1000);
+    }, 1500);
     return () => {
       clearInterval(interval);
     };
@@ -264,7 +268,9 @@ const Timetable = ({
 
   return (
     <>
-      <h2 style={{ textAlign: "center" }}>Login as {user}</h2>
+      <h2 style={{ textAlign: "center" }}>ITSC 学 生 助 理 抢 班 系 统</h2>
+      <h3 style={{ textAlign: "center" }}>Login as {user}</h3>
+      <h3 style={{ textAlign: "center" }}>请勿在短时间内多次操作同一时段的选择，选择后请耐心等待状态更新以确认是否选择成功</h3>
       <div
         align="center"
         ref={ref}
@@ -273,7 +279,7 @@ const Timetable = ({
           overflow: "scroll",
         }}
         onInput={handleInput}
-      ></div>{" "}
+      ></div>
       {!hideDownloadButton && (
         <p style={{ display: "flex", justifyContent: "center" }}>
           <button onClick={DownloadMarks}>Download Selection</button>
diff --git a/components/UserInputWrap.tsx b/components/UserInputWrap.tsx
index 42c82e4..dec1e2f 100644
--- a/components/UserInputWrap.tsx
+++ b/components/UserInputWrap.tsx
@@ -6,7 +6,7 @@ const UserInputWrap = ({ children, setUser }) => {
   const [begin, setBegin] = React.useState(false);
 
   React.useEffect(() => {
-    setInputUser(localStorage.getItem("user") || "");
+    setInputUser(localStorage.getItem("username") || "");
   }, []);
 
   return (
@@ -17,9 +17,10 @@ const UserInputWrap = ({ children, setUser }) => {
             display: "grid",
             placeItems: "center",
             alignItems: "center",
-            minHeight: "100vh",
+            // minHeight: "100vh",
           }}
         >
+          <h2 style={{ textAlign: "center" }}>ITSC 学 生 助 理 抢 班 系 统</h2>
           <div>
             <input
               style={{
@@ -45,7 +46,7 @@ const UserInputWrap = ({ children, setUser }) => {
                 }
                 setUser(inputUser.trim());
                 setBegin(true);
-                localStorage.setItem("user", inputUser.trim());
+                localStorage.setItem("username", inputUser.trim());
               }}
             >
               Login
diff --git a/data.zip b/data.zip
new file mode 100644
index 0000000..e03d9bf
Binary files /dev/null and b/data.zip differ
diff --git a/package.json b/package.json
index c3afce1..36ddace 100644
--- a/package.json
+++ b/package.json
@@ -4,7 +4,7 @@
   "private": true,
   "scripts": {
     "esbuild": "./node_modules/.bin/esbuild  --bundle --tsconfig=entrypoints/tsconfig.json --alias:'@'='./' --outdir=entrypoints --splitting --format=esm entrypoints/index.tsx entrypoints/edit/index.tsx entrypoints/report/index.tsx entrypoints/control/index.tsx --minify",
-    "dev": "next dev",
+    "dev": "next dev -p 4000",
     "build": "next build",
     "start": "next start -p 4000",
     "lint": "next lint"
diff --git a/pages/api/record.ts b/pages/api/record.ts
index c0472cc..518fd90 100644
--- a/pages/api/record.ts
+++ b/pages/api/record.ts
@@ -22,25 +22,35 @@ export default function handler(req: NextApiRequest, res: NextApiResponse) {
           count += 1;
           if (count >= config.limit) {
             res.status(403).json({
-              error: `超过选择数量限制，您至多选 ${config.limit} 个班.`,
+              error: `超过选择数量限制，您至多选 ${config.limit} 个班次`,
             });
             return;
           }
         }
       }
-      // check whether it is already occupied
-      if (store[json.name] !== undefined) {
+      // check whether the user repeatly select
+      if (store[json.name] === json.user) {
+        console.log("api::request: repeat select", json);
         res.status(403).json({
-          error: `当前位置已被他人占用`,
+          error: `您已经选择了这个班次，请勿重复选择`,
+        });
+        return;
+      }
+      // check whether it is already occupied
+      else if (store[json.name] !== undefined) {
+        console.log("api::request: occupied", json);
+        res.status(403).json({
+          error: `当前位置已被他人占用，请选择其他班次`,
         });
         return;
       }
       store[json.name] = json.user;
     } else {
+      // console.log(store, json);
       // check whether the request name match the taken name
       if (store[json.name] !== json.user) {
         res.status(403).json({
-          error: `失败：您未选择到当前位置`,
+          error: `您已经取消了这个班次，请勿重复点击复选框`,
         })
         return;
       }
diff --git a/pages/index.tsx b/pages/index.tsx
index 7d9c67c..595bd60 100644
--- a/pages/index.tsx
+++ b/pages/index.tsx
@@ -10,8 +10,8 @@ export default function Home() {
     <>
       <Head>
         <title>抢 班</title>
-        <meta name="description" content="ITSC抢班系统" />
-        {/* <meta name="viewport" content="width=device-width, initial-scale=1" /> */}
+        <meta name="description" content="ITSC 学 生 助 理 抢 班 系 统" />
+        <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no" />
         <link rel="icon" href="/favicon.ico" />
       </Head>
       <main>
diff --git a/pages/report-tool.tsx b/pages/report-tool.tsx
index 8e1b7ce..b71f232 100644
--- a/pages/report-tool.tsx
+++ b/pages/report-tool.tsx
@@ -1,14 +1,13 @@
 import React from "react";
 import Head from "next/head";
+import { get, post } from "@/common";
 
 const ReportPage = () => {
   const ref = React.useRef();
   const getReport = async () => {
-    const resp = await fetch("/api/html").then((resp) => resp.json());
+    const resp = await get("/api/html");
     ref.current.innerHTML = resp.html;
-    const json: Record<string, string> = await fetch("/api/tool").then((resp) =>
-      resp.json()
-    );
+    const json: Record<string, string> = await get("/api/tool");
     const table = ref.current.children[0];
     const tbody = table.children[table.children.length - 1];
     for (const tr_index in tbody.children) {
diff --git a/pages/report.tsx b/pages/report.tsx
index edf2dae..69489cd 100644
--- a/pages/report.tsx
+++ b/pages/report.tsx
@@ -1,14 +1,13 @@
 import React from "react";
 import Head from "next/head";
+import { get, post } from "@/common";
 
 const ReportPage = () => {
   const ref = React.useRef();
   const getReport = async () => {
-    const resp = await fetch("/api/html").then((resp) => resp.json());
+    const resp = await get("/api/html");
     ref.current.innerHTML = resp.html;
-    const json: Record<string, string> = await fetch("/api/admin").then(
-      (resp) => resp.json()
-    );
+    const json: Record<string, string> = await get("/api/admin");
     const table = ref.current.children[0];
     const tbody = table.children[table.children.length - 1];
     for (const tr_index in tbody.children) {
diff --git a/pages/tool.tsx b/pages/tool.tsx
index d6089ab..f94a63f 100644
--- a/pages/tool.tsx
+++ b/pages/tool.tsx
@@ -7,7 +7,7 @@ export default function Home() {
   const [begin, setBegin] = React.useState(false);
 
   React.useEffect(() => {
-    setUser(localStorage.getItem("user") || "");
+    setUser(localStorage.getItem("username") || "");
   }, []);
 
   return (
@@ -34,7 +34,7 @@ export default function Home() {
                 }
                 setUser(user.trim());
                 setBegin(true);
-                localStorage.setItem("user", user);
+                localStorage.setItem("username", user);
               }}
             >
               Login