diff --git a/duetector/tracers/base.py b/duetector/tracers/base.py
index 38f638c..fab3356 100644
--- a/duetector/tracers/base.py
+++ b/duetector/tracers/base.py
@@ -45,12 +45,12 @@ class BccTracer(Tracer):
     """
     A Tracer use bcc.BPF host
 
-    attatch_type: str  attatch type for bcc.BPF, e.g. kprobe, kretprobe, etc.
-    attatch_args: Dict[str, str]  args for attatch function
+    attatch_type: str  attatch type for bcc.BPF, e.g. kprobe, kretprobe
+    attatch_args: Dict[str, str] args for attatch function
     poll_fn: str  poll function name in bcc.BPF
-    poll_args: Dict[str, str]  args for poll function
-    prog: str  bpf program
-    data_t: NamedTuple  data type for this tracer
+    poll_args: Dict[str, str] args for poll function
+    prog: str bpf program
+    data_t: NamedTuple data type for this tracer
 
     set_callback should attatch callback to bpf, translate raw data to data_t then call the callback
     # FIXME: Maybe it's hard for using? Maybe we should use a more simple way to implement this?