upper trough (upper-level trough)
upper trough lower trough coupling
Wiring Trough， Wiring Groove， Cable Trough
at the eastern foot of Helan Mountain
Eastern foot of Helan Mountain
eastern foot of Helan Moutain
Helan Mountain 750 kV Substation
Helan Mountain Nature Reserve
Helan National Nature Reserve
Helan-Chuandian SN tectonic zone
Northern Helan Mountain
the middle of the Helan Mountains