Arụ ọrụ nke coal n'okpuru ala, ọnọdụ ọrụ siri ike ma sie ike, gburugburu ebe obibi siri ike, ibu na-agbanwe na mgbanwe nke ọnọdụ geological, oke ọrụ ahụ nwere oke, enwere nkukota, nkukota na ọdịda na ihe egwu ndị ọzọ, enwere mmiri. mmiri, mmanụ, emu...
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