diff --git a/aof/rewrite.go b/aof/rewrite.go
index ad073cd..78dd59d 100644
--- a/aof/rewrite.go
+++ b/aof/rewrite.go
@@ -151,7 +151,7 @@ func (handler *Handler) FinishRewrite(ctx *RewriteCtx) {
 	}
 	handler.aofFile = aofFile
 
-	// reset selected db 重新写入一次 select 指令保证 aof 中的数据库与 handler.currentDB 一致
+	// write select command again to ensure aof file has the same db index with  handler.currentDB
 	data = protocol.MakeMultiBulkReply(utils.ToCmdLine("SELECT", strconv.Itoa(handler.currentDB))).ToBytes()
 	_, err = handler.aofFile.Write(data)
 	if err != nil {
diff --git a/database/keys.go b/database/keys.go
index 9146cd8..f36452c 100644
--- a/database/keys.go
+++ b/database/keys.go
@@ -294,7 +294,7 @@ func execKeys(db *DB, args [][]byte) redis.Reply {
 func toTTLCmd(db *DB, key string) *protocol.MultiBulkReply {
 	raw, exists := db.ttlMap.Get(key)
 	if !exists {
-		// 无 TTL
+		// has no TTL
 		return protocol.MakeMultiBulkReply(utils.ToCmdLine("PERSIST", key))
 	}
 	expireTime, _ := raw.(time.Time)
diff --git a/database/replication.go b/database/replication.go
index 3128ff1..72d7cfd 100644
--- a/database/replication.go
+++ b/database/replication.go
@@ -309,6 +309,7 @@ func (mdb *MultiDB) doPsync() error {
 	}
 	// there is no CRLF between RDB and following AOF, reset stream to avoid parser error
 	mdb.replication.masterChan = parser.ParseStream(mdb.replication.masterConn)
+	// fixme: update aof file
 	return nil
 }