Here in Malta English is one of the national languages (together with Maltese, our national language, which has common roots with Arabic but also lots of influences from our European neighbours' languages, especially Italian). We start learning it from a very early age; officially from the first year of primary school, but a lot of families start speaking in English to their children from infancy (with the consequence that such children sometimes never learn Maltese correctly...)
It's not easy to speak solely in Maltese nowadays - some words have practically become discourse markers or they are always used instead of their Maltese equivalents - I don't have any statistics, but it's MUCH more common to hear somebody say "sorry" than the Maltese "skuzani", for example. Numbers too are almost always in English - one almost has to make a conscious effort to say them in Maltese.
With regards to people who speak in both languages at once (interspersing their native language with English words, that is) - it's a phenomenon called code-switching or code-mixing (there is a slight difference between the two, but it's not very important ^^

. It is very common in places which were colonised - the language of the ruling power has more prestige, and thus people start to include some of its words in their discourse. According to one of my lecturers it's almost impossible to avoid it in such situations. It still bugs me when Maltese people either speak in English purely to seem "better" (though it's funny to find their mistakes :lolsign

. I like English a lot (I teach it, in fact) but I still think that we should be proud of our own language.
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