Observe within the first position that sooner than has an analogous that means in all of [i-iii] . Sec­ ondly, it takes an identical modifiers in those 3 contexts. lets, for instance, insert such goods as lengthy, presently, an hour, a short time in entrance of prior to in all 3 examples in [4] . the adaptation among the 3 circumstances of earlier than is hence completely a question of the supplement. Nowhere else within the grammar is a part-of-speech contrast dependent in basic terms on a distinction of this type. Our extension of the preposition class contains redrawing the limits among prepositions and subordinators, and among prepositions and adverbs. We take in those pairs in flip. 2. 1 Prepositions vs subordinators the normal category of subordinating conjunctions includes (among others) the phrases in [5] : [5] i after ii a. even though b. if; prior to simply because that seeing that ifc no matter if until eventually lest till supplied notwithstanding until we have to distinguish phrases with the form if. One has a conditional that means, as in I 'll assist you if [ can: we express this above as ifc. the opposite happens in subordinate interrogative clauses like See ifthere are any vacancies, such as major clause A re there any vacancies ? : we convey it as i/;. it is a variation of even if: examine See no matter if there are any vacancies. 1 30 bankruptcy 7 Prepositions and preposition words The phrases in [i] usually belong to the preposition classification to boot, while these in [ii] don't. we've got argued opposed to a twin category therapy of the [i] phrases, analysing them easily as prepositions that license other kinds of supplement. yet when we re-examine the excellence among prepositions and subordinators we discover there are reliable purposes for reassigning the phrases in [iia] besides to the preposition classification. This leaves a truly small subordinator type, with that, even if and ifi as its major contributors. the key argument for drawing the boundary among prepositions and subor­ dinators among [iia] and [iib] is that that, even if and ifi functionality as markers of subordination while the opposite phrases in [5] functionality as heads of the elements they introduce. think of the subsequent examples: a. i believe [(that) she 's most likely right]. b. I don 't understand [whether they've got obtained our letter yet]. ii a. She stayed at the back of for a couple of minutes [after the others had left]. b. They complained [because we didn 't end the activity this week]. [6] In [i] the bracketed parts are subordinate clauses with that and even if easily marking the subordination: the most clause opposite numbers are She is prob­ ably correct (declarative) and feature they bought our letter but ? (interrogative). during this context the that's non-compulsory (as indicated through the parentheses): the clause is within the place of supplement to imagine, so it's not compulsory to mark its subordi­ nate prestige in its personal constitution. no matter if isn't omissible since it marks the clause as interrogative in addition to subordinate: it is only with the default declara­ tive variety that the subordinator is usually not obligatory.