Blackout occurred in interconnected North America power grid

constructing the network for suddenly - occurred public health incident

Continuously occurred earthquakes

earthquakes occurred in groups

fault occurred after rezeroing

fault occurred during seek

frequently occurred problems

Naturally occurred diploid

Obstruction occurred

occurred discipline of the main insect pests

Occurred law

occurred regularity

occurred time

often occurred malfunction

Preliminary occurred

Status of occupational diseases occurred

Suddenly occurred public health incident

trip-occurred