This technique enables extraction of fuel from small, difficult-to-access coal seams, and could double the world's current coal reserves.
这项技术可以从窄而难以进入的煤层中提取燃煤，并可能使目前世界上的煤炭储量增加一倍。
2
For decades, scientists have strived to collect sediment cores from the difficult-to-access Arctic Ocean floor, to discover what the Arctic was like in the past.
几十年来，科学家们致力于在难以介入的北冰洋底收集沉积物岩心，以期了解北极过去的情况。
3
Large dunes make accessto the beach difficult in places.