diff --git a/event/connection.c b/event/connection.c
index cb2937a..f488bce 100644
--- a/event/connection.c
+++ b/event/connection.c
@@ -41,7 +41,6 @@ int conn_pool_init(mem_pool *p, int size)
     return FCY_OK;
 }
 
-/* 从空闲链表中取出一个连接 */
 connection *conn_get()
 {
     list_node   *head;
diff --git a/event/connection.h b/event/connection.h
index c3af9f0..6254f78 100644
--- a/event/connection.h
+++ b/event/connection.h
@@ -1,5 +1,7 @@
 //
 // Created by frank on 17-2-12.
+// TCP connection pool
+// the size of pool is determined by worker connection configuration
 //
 
 #ifndef FANCY_CONN_POOL_H
@@ -12,26 +14,27 @@
 typedef struct connection connection;
 typedef struct connection peer_connection;
 
-/* call conn_get to get a connection */
 struct connection {
 
     int                 sockfd;
     event               read;
     event               write;
 
-    peer_connection     *peer;  // 上游/下游连接
+    peer_connection     *peer;  // user or upstream connection
 
     void                *app;   // request, upstream
     int                 app_count;
 
-    struct sockaddr_in  addr;
+    struct sockaddr_in  addr;   // peer address
 
     list_node           node;
 };
 
 int conn_pool_init(mem_pool *p, int size);
 
+/* conn_get is the only way to get a connection */
 connection *conn_get();
+
 void conn_free(connection *conn);
 char *conn_str(connection *conn);
 
diff --git a/event/event.c b/event/event.c
index 2ce4f61..6923ce7 100644
--- a/event/event.c
+++ b/event/event.c
@@ -51,7 +51,7 @@ int event_process(timer_msec timeout)
         return FCY_ERROR;
     }
     else if (n_ev == 0) {
-        /* 超时 */
+        /* timeout */
         return 0;
     }
 
@@ -60,7 +60,7 @@ int event_process(timer_msec timeout)
         events = e_event->events;
         conn = e_event->data.ptr;
 
-        /* 检测到错误或者对端关闭连接，交给read_handler或者write_handler解决 */
+        /* error detected, throw it to read_handler or write_handler */
         if (events & (EPOLLERR | EPOLLRDHUP)) {
             events |= EPOLLIN | EPOLLOUT ;
         }
@@ -72,7 +72,7 @@ int event_process(timer_msec timeout)
 
         wevent = &conn->write;
         if (wevent->active && (events & EPOLLOUT)) {
-            // 忽略过期事件
+            // ignore timeout event
             if (conn->sockfd == -1) {
                 continue;
             }
diff --git a/event/event.h b/event/event.h
index 04ac22d..057791c 100644
--- a/event/event.h
+++ b/event/event.h
@@ -17,9 +17,9 @@ typedef void (*event_handler)(event *);
 
 struct event {
 
-    unsigned        active:1;     // 是否在epoll_wait中
-    unsigned        timer_set:1;  // 是否在定时器中
-    unsigned        timeout:1;    // 是否为超时事件
+    unsigned        active:1;     // is in epoll_wait ?
+    unsigned        timer_set:1;  // is in timer ?
+    unsigned        timeout:1;    // is timeout ?
 
     rbtree_node     rb_node;
 
diff --git a/event/timer.c b/event/timer.c
index 5951006..3047669 100644
--- a/event/timer.c
+++ b/event/timer.c
@@ -84,18 +84,19 @@ static timer_msec timer_recent()
     rbtree_node *recent;
     timer_msec  current;
 
-    /* 计时器为空, 表示不会有任何事件发生 */
+    /* no event is waiting */
     if (rbtree_empty(&timer)) {
         return TIMER_INFINITE;
     }
 
     recent = rbtree_min(&timer);
     current = current_msec();
-    if (current < recent->key) {    /* 没有事件发生，返回最近事件的时间差值 */
+    if (current < recent->key) {
+        /* event will be timeout in the future */
         return recent->key - current;
     }
 
-    /* 有事件发生 */
+    /* event already timeout */
     return 0;
 }
 
diff --git a/http/http.c b/http/http.c
index 9686357..a3d59a3 100644
--- a/http/http.c
+++ b/http/http.c
@@ -11,14 +11,14 @@
 #include "request.h"
 #include "upstream.h"
 
-/* 通用的handler */
+/* generic handler */
 static void accept_h(event *);
 static void read_request_headers_h(event *);
 static void parse_request_h(event *);
 static void read_request_body(event *);
 static void process_request_h(event *);
 
-/* 专门处理动态内容的 handler */
+/* dynamic content handler */
 static void peer_connect_h(event *);
 static void upstream_write_request_h(event *);
 static void upstream_read_response_header_h(event *);
@@ -29,7 +29,7 @@ static void write_response_all_h(event *);
 static void write_response_headers_h(event *);
 static void send_file_h(event *);
 
-/* 表示一个请求处理完成，可能关闭连接，也可能keep_alive */
+/* a request is finished, connection can be closed or keep alive */
 static void finalize_request_h(event *);
 
 static void response_and_close(connection *conn, int status_code);