diff --git a/dpdata/driver.py b/dpdata/driver.py
index b446a5e83..de72d3fe7 100644
--- a/dpdata/driver.py
+++ b/dpdata/driver.py
@@ -125,6 +125,7 @@ class HybridDriver(Driver):
     ...     {"type": "sqm", "qm_theory": "DFTB3"},
     ...     {"type": "dp", "dp": "frozen_model.pb"},
     ... ])
+
     This driver is the hybrid of SQM and DP.
     """
 
diff --git a/dpdata/plugins/deepmd.py b/dpdata/plugins/deepmd.py
index 26cdc3824..6953aba53 100644
--- a/dpdata/plugins/deepmd.py
+++ b/dpdata/plugins/deepmd.py
@@ -82,10 +82,12 @@ class DeePMDMixedFormat(Format):
     Examples
     --------
     Dump a MultiSystems into a mixed type numpy directory:
+
     >>> import dpdata
     >>> dpdata.MultiSystems(*systems).to_deepmd_npy_mixed("mixed_dir")
 
     Load a mixed type data into a MultiSystems:
+
     >>> import dpdata
     >>> dpdata.MultiSystems().load_systems_from_file("mixed_dir", fmt="deepmd/npy/mixed")
     """
@@ -161,6 +163,7 @@ class DeePMDHDF5Format(Format):
     Examples
     --------
     Dump a MultiSystems to a HDF5 file:
+
     >>> import dpdata
     >>> dpdata.MultiSystems().from_deepmd_npy("data").to_deepmd_hdf5("data.hdf5")
     """
diff --git a/dpdata/system.py b/dpdata/system.py
index 7b68a9e10..171cd81a6 100644
--- a/dpdata/system.py
+++ b/dpdata/system.py
@@ -831,6 +831,7 @@ def predict(self, *args: Any, driver: str = "dp", **kwargs: Any) -> "LabeledSyst
         Examples
         --------
         The default driver is DP:
+
         >>> labeled_sys = ori_sys.predict("frozen_model_compressed.pb")
         """
         if not isinstance(driver, Driver):
@@ -1406,6 +1407,7 @@ def minimize(
         Examples
         --------
         Minimize a system using ASE BFGS along with a DP driver:
+
         >>> from dpdata.driver import Driver
         >>> from ase.optimize import BFGS
         >>> driver = driver.get_driver("dp")("some_model.pb")