The main function of the lubrication system in to enable （） of a film of oil between the moving parts. ["the information","the formation","the scatter","the frictio"]
全向天线无法（）下倾，因此很高的全向站应该根据不同情况选择带不同角度的（）下倾天线。
When the movement of engine is no longer required the pilot usually gives the order like this（） . ["Stop engine","Nothing to port","Finish engines","Finished with engine"]
简述何谓焦炉老化？
The main factor which determines the output of each cylinder is （） ["the cylinder weight","the cylinder bore","the cylinder length","the cylinder cover"]
郊区和农村：定向天线选用水平半功率波瓣宽度为（），垂直半功率波瓣宽度为（）的天线，天线的增益在（）之间。全向天线采用垂直半功率波瓣宽度为（），增益在（）之间的天线。
