What happens if I don't know a word or construction in a prose composition question?

Prose composition is in many ways more daunting than unseen translation, since you'll be translating from a more comfortable language into a less comfortable one rather than vice versa. You may therefore come across a word or phrase in the English passage which you can't immediately put into Latin, perhaps because you don't know the word or because the construction is slightly awkward. In this scenario it is useful to step back and look at the wider implication of the phrase, rather than the specific way in which it is expressed in the English: there may be an alternative way of phrasing it in English which carries the same meaning but which you'd feel more comfortable putting into Latin. Let's take this phrase from the OCR sample paper: "By reciting warlike poems, Tyrtaeus restored the soldiers' courage." A straightforward translation of this would be,Tyrtaeus, carminibus bellicosis recitatis, virtutem militum refecit, with the ablative absolute explaining how the action of the main clause was carried out. A viable alternative for this if, say, you cannot remember how to form the ablative absolute would be to use the ablative of the gerund:Tyrtaeus carmina bellicosa recitando virtutem militum refecitThe construction is basically same, with the instrumental action expressed in a slightly different way.But what if, for example, you simply cannot think of a way to form this kind of construction ("he did X by doing Y")? Here, try and think of another construction to link the subordinate clause with the main clause whilst retaining the meaning of the English. You could use a purpose clause, for example: "Tyrtaeus recited warlike poems in order to restore the soldiers' courage" - Tyrtaeus carmina bellicosa recitavit ut virtutem militum reficeret The meaning is still the same, it has just been expressed in a different way. These measures should only be used if you genuinely can't remember how to form the immediately obvious construction, and your new rendering should always be sufficiently close to the meaning of the original. That said, however, a fluent, grammatically-correct translation is always preferable to a botched attempt to translate the original when you can't remember the right vocab and syntax (remember those marks for style!).