diff --git a/magicoca/__init__.py b/magicoca/__init__.py
index ac10b42..d0690cf 100644
--- a/magicoca/__init__.py
+++ b/magicoca/__init__.py
@@ -1,6 +1,6 @@
 from multiprocessing import set_start_method
-from multiprocessing.connection import wait
-from typing import Any, Callable, Generator
+from multiprocessing.connection import wait, Connection
+from typing import Generator
 
 from magicoca.chan import Chan, T, NoRecvValue
 
@@ -13,18 +13,29 @@ set_start_method("spawn", force=True)
 
 def select(*args: Chan[T]) -> Generator[T, None, None]:
     """
-    Return a yield, when a value is received from one of the channels.
-    Args:
-        args: channels
+    当其中一个通道接收到数据时，yield 该数据。
+
+    参数:
+        args: 多个 Chan 对象
     """
-    pipes = [ch.recv_conn for ch in args if not ch.is_closed]
+    # 构造管道到通道列表的映射，避免重复的 recv_conn 对象
+    pipe_to_chs: dict[Connection, list[Chan[T]]] = {}
+    for ch in args:
+        if not ch.is_closed:
+            pipe: Connection = ch.recv_conn
+            pipe_to_chs.setdefault(pipe, []).append(ch)
+    pipes: list[Connection] = list(pipe_to_chs.keys())
 
     while pipes:
-        ready_pipes = wait(pipes)
+        ready_pipes: list[Connection] = wait(pipes) # type: ignore
         for pipe in ready_pipes:
-            for ch in args:
-                if ch.recv_conn == pipe:
-                    if not isinstance(value := ch.recv(0), NoRecvValue):
-                        yield value
-                    if ch.is_closed:
-                        pipes.remove(pipe)
\ No newline at end of file
+            # 遍历所有使用该管道的通道
+            channels: list[Chan[T]] = list(pipe_to_chs.get(pipe, []))
+            for ch in channels:
+                if not isinstance(value := ch.recv(0), NoRecvValue):
+                    yield value
+                if ch.is_closed:
+                    pipe_to_chs[pipe].remove(ch)
+            # 如果该管道已没有活跃的通道，则移除
+            if not pipe_to_chs[pipe]:
+                pipes.remove(pipe)
\ No newline at end of file
diff --git a/magicoca/chan.py b/magicoca/chan.py
index bb80e78..be7a0b5 100644
--- a/magicoca/chan.py
+++ b/magicoca/chan.py
@@ -47,13 +47,13 @@ class Chan(Generic[T]):
         """
         self.send_conn.send(value)
 
-    def recv(self, timeout: float | None = None) -> T | None | NoRecvValue:
+    def recv(self, timeout: float | None = None) -> T | NoRecvValue:
         """Receive a value from the channel.
         If the timeout is None, it will block until a value is received.
         If the timeout is a positive number, it will wait for the specified time, and if no value is received, it will return None.
         接收通道中的值。
         如果超时为None，则它将阻塞，直到接收到值。
-        如果超时是正数，则它将等待指定的时间，如果没有接收到值，则返回None。
+        如果超时是正数，则它将等待指定的时间，如果没有接收到值，则返回NoRecvValue。
         Args:
             timeout:
                 The maximum time to wait for a value.
@@ -82,7 +82,7 @@ class Chan(Generic[T]):
         """
         return self
 
-    def __next__(self) -> T:
+    def __next__(self) -> T | NoRecvValue:
         return self.recv()
 
     def __lshift__(self, other: T):
@@ -95,7 +95,7 @@ class Chan(Generic[T]):
         self.send(other)
         return self
 
-    def __rlshift__(self, other: Any) -> T:
+    def __rlshift__(self, other: Any) -> T | NoRecvValue:
         """
         << chan
         Returns: The value received from the channel.
diff --git a/tests/test_select.py b/tests/test_select.py
index 8c0513c..7f65d06 100644
--- a/tests/test_select.py
+++ b/tests/test_select.py
@@ -4,41 +4,35 @@ from multiprocessing import Process
 from magicoca import Chan, select
 
 
-def sp1(chan: Chan[int]):
-    for i in range(10):
-        chan << i << i * 2
-
-
-def sp2(chan: Chan[int]):
-    for i in range(10):
-        chan << i << i * 3
-
-
-def rp(chans: list[Chan[int]]):
-    rl = []
-    for t in select(*chans):
-        rl.append(t)
-        if len(rl) == 40:
-            break
-    print(rl)
-
 def send_process(chan: Chan[int], _id: int):
-    while True:
-        chan << _id
-        time.sleep(2)
+    for i in range(10):
+        chan << i
+        time.sleep(0.1 * _id)
 
 def recv_process(chan_list: list[Chan[int]]):
+    c = []
     for t in select(*chan_list):
-        print(t)
-
-
+        c.append(t)
+        print("Select", t)
+        if len(c) == 30:
+            break
 class TestSelect:
     def test_select(self):
-        chan_list = []
-        for i in range(10):
-            chan = Chan[int]()
-            chan_list.append(chan)
-            p = Process(target=send_process, args=(chan, i))
-            p.start()
-        p = Process(target=recv_process, args=(chan_list,))
-        p.start()
+        ch1 = Chan[int]()
+        ch2 = Chan[int]()
+        ch3 = Chan[int]()
+
+        p1 = Process(target=send_process, args=(ch1, 1))
+        p2 = Process(target=send_process, args=(ch2, 2))
+        p3 = Process(target=send_process, args=(ch3, 3))
+        p4 = Process(target=recv_process, args=([ch1, ch2, ch3],))
+
+        p1.start()
+        p2.start()
+        p3.start()
+        p4.start()
+
+        p1.join()
+        p2.join()
+        p3.join()
+        p4.join()