“Schmidt (2001) argues that it ‘largely determines the course of language development’ ” (lines 18-20) “It should be remembered that advocates of both CLT and TBLT have been using the term context mainly to refer to linguistic and pragmatic features of language and language use.” (lines 27-30)
The author intended to emphasize the words ‘determines’ and ‘context’ as they had been mentioned previously.
The author italicized the word ‘determines’ to stress the idea of causation; the italics in ‘context’ substitutes for quotation marks.
The words ‘determines’ and ‘context’ were italicized for emphasis since they represent ideas exposed by others, not the author himself.
The italics in the term ‘context’ refers to a newly-coined term in LT methodology; the word ‘determines’ in italics reveals that Schmidt was too authoritative in choosing this term.
Both words (‘determines’ and ‘context’) are terms employed by others and explained by the author of this text.