Synthetic fuel the fuel, and the fuel is less dense than conventional jet fuel allowing aircraft to fly further on the same load of fuel. The "cleanness" of these FT synthetic fuels is further demonstrated by the fact that they are sufficiently non-toxic and environmentally benign as to be considered biodegradable. This owes primarily to the near-absence of sulfur and extremely low level of aromatics present in the fuel. One concern commonly raised about the development of synthetic fuels plants is sustainability. Fundamentally, transitioning from oil to coal or natural gas for transportation fuels production is a transition from one inherently depletable
Interlanguage fossilization to learning second language, and the relationship of fossilization to the learner's communicative needs. Arguments have emerged regarding adult learners' general lack of empathy with target language native speakers and culture. According to Guiora et al., adults do not have the motivation to change their accent and to acquire native-like pronunciation. Unlike children, who are generally more open to target language culture, adults have more rigid language ego boundaries. Thus, adults may be inclined to establishing their pre-existing cultural and ethnic identity, and this they do by maintaining their stereotypical accent. Notwithstanding this, there is a lack of needed research,