Which pairs of lines casts doubt on the certainty the speaker felt when choosing one path over the other?

what do you mean

as we know, the english language is spoken all over the world by native and non-native speakers and has become the most certain tool when it comes to communicating. businesses, schools, even romantic relationships depend on it to keep thriving. in addition, it is the language of the internet not only because most of the content available is in english, but also because people prefer to use it when talking to others, since it's the language everyone supposedly learns.

yet, there have been some current claims that chinese will soon take over as the most important language in the world. china's magnitude has never been more evident and doing business with the chinese is a gold mine for any country. we now see language schools offering chinese courses as commonly as english.

however - even though we cannot deny china's importance and the advantage it is when someone takes the time to learn the language their business contact speaks-, people in general seem to be ignoring the aspects that seem to keep english as the chosen one of languages. one of them has been mentioned above: it is the language of the internet. also, chinese people are still learning english, since it opens doors in communicating with practically everyone else, from every single country.

note: if this is not the sort of transition you need, let me know. : d