Help! Unable to launch model in GAZEBO:the model does not appear on Gazebo.

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hi,guys, i'm a beginner with ROS world.

I use Ubuntu 18.04 ,melodic, gazebo 9.

When i execute roslaunch gazebo.launch, Gazebo starts and models of the 3D world appear, but there is no my model!

The terminal give me this error:

[spawn_model-8] process has died [pid 4832, exit code 1, cmd /opt/ros/melodic/lib/gazebo_ros/spawn_model -file /home/hanke/catkin_ws/src/car/urdf/car.urdf -urdf -model car __name:=spawn_model __log:=/home/hanke/.ros/log/64258e90-5b29-11ea-9b5f-d0577baf2963/spawn_model-8.log].
log file: /home/hanke/.ros/log/64258e90-5b29-11ea-9b5f-d0577baf2963/spawn_model-8*.log

It works well before i catkin_make my cw, HOW should I solve this Problem? THANK YOU