Fuel oil and related equipment which were often designed for lighter fuels. For comparison, BS 2869 Class G heavy fuel oil behaves in similar fashion, requiring storage at , pumping at around and finalising for burning at around . Most of the facilities which historically burned No. 6 or other residual oils were industrial plants and similar facilities constructed in the early or mid 20th century, or which had switched from coal to oil fuel during the same time period. In either case, residual oil was seen as a good prospect because it was cheap and readily available. Most of these facilities
Interlanguage fossilization advance gradually until it becomes equivalent, or nearly equivalent, to the target language. However, during the second language learning process, an interlanguage may reach one or more temporary restricting phases when its development appears to be detained. A permanent cessation of progress toward the target language has been referred to as fossilization. This linguistic phenomenon, interlanguage fossilization, can occur despite all reasonable attempts at learning. Fossilization includes those items, rules, and sub-systems that second language learners tend to retain in their interlanguage, that is, all those aspects of interlanguage that become entrenched and permanent, and that the majority of second