diff --git a/fastNLP/core/metrics.py b/fastNLP/core/metrics.py
index f994bd31..77695852 100644
--- a/fastNLP/core/metrics.py
+++ b/fastNLP/core/metrics.py
@@ -22,7 +22,7 @@ from .utils import _check_arg_dict_list
 from .utils import _get_func_signature
 from .utils import seq_len_to_mask
 from .vocabulary import Vocabulary
-
+from abc import abstractmethod
 
 class MetricBase(object):
     """
@@ -117,10 +117,12 @@ class MetricBase(object):
     def __init__(self):
         self.param_map = {}  # key is param in function, value is input param.
         self._checked = False
-    
+
+    @abstractmethod
     def evaluate(self, *args, **kwargs):
         raise NotImplementedError
-    
+
+    @abstractmethod
     def get_metric(self, reset=True):
         raise NotImplemented
     
diff --git a/reproduction/seqence_labelling/cws/model/module.py b/reproduction/seqence_labelling/cws/model/module.py
index 6cd8b5e3..86149f39 100644
--- a/reproduction/seqence_labelling/cws/model/module.py
+++ b/reproduction/seqence_labelling/cws/model/module.py
@@ -1,11 +1,10 @@
 from torch import nn
 import torch
-from fastNLP.modules import Embedding
 import numpy as np
 
 class SemiCRFShiftRelay(nn.Module):
     """
-    该模块是一个decoder，但
+    该模块是一个decoder，但当前不支持含有tag的decode。
 
     """
     def __init__(self, L):
diff --git a/reproduction/seqence_labelling/cws/train_shift_relay.py b/reproduction/seqence_labelling/cws/train_shift_relay.py
index ed512252..c5d436fe 100644
--- a/reproduction/seqence_labelling/cws/train_shift_relay.py
+++ b/reproduction/seqence_labelling/cws/train_shift_relay.py
@@ -32,7 +32,7 @@ lr = 0.02
 #########hyper
 device = 0
 
-# !!!!这里前往不要放完全路径，因为这样会暴露你们在服务器上的用户名，比较危险。所以一定要使用相对路径，最好把数据放到
+# !!!!这里千万不要放完全路径，因为这样会暴露你们在服务器上的用户名，比较危险。所以一定要使用相对路径，最好把数据放到
 #   你们的reproduction路径下，然后设置.gitignore
 file_dir = '/path/to/pku'
 char_embed_path = '/path/to/1grams_t3_m50_corpus.txt'