The use of quin and quominus is infamously tricky, but if you can deploy them in your prose composition it will make your work appear idiomatic and, therefore, sophisticated as well as indicative of a solid understanding of the language.
We are concerned here with clauses of hindering and prevention e.g. I stop you from doing x, I delay you from doing y and so forth. Note the translation ‘from’, this is how you will almost always want to render quin or quominus if you come across either word in an unprepared translation.
The most common verbs which take quin and/or quominus are as follows;
verbs of preventing - impedio (I hinder), retineo (I restrain) and deterreo (I deter)
verbs of refraining (only to be used in negative clauses) – mihi tempero (I refrain), recuso (I object), dubito (I hesitate)
quin and quominus (sometimes written as two words, quo minus) are always followed by the subjunctive – present subjunctive in primary sequence, imperfect subjunctive in historic sequence
The difference between the two words is that quin can only be used with a negative main clause, whereas quominus can be used with clauses both negative and positive. N.B. preferably you’ll use quin with a negative main clause and quominus with a positive one to indicate that you understand this difference.
tempestas Augustum deterruit quominus Graeciam navigaret
The bad weather discouraged Augustus from sailing to Greece
-deterruit – not accompanied by a negative thus main clause is positive, therefore you should quominus
- navigaret – deterruit is perfect tense so we are in historic sequence. Therefore navigaret must be imperfect subjunctive
M. Antonius numquam sibi temperat quin nimis vini bibat
Mark Anthony never restrains himself from drinking too much wine
-numquam – this makes the main clause negative and so you should use quin
-bibat - temperat is present tense so we are in primary sequence. Therefore bibat must be present subjunctive
Finally, using quin and quominus accurately will really convey to the examiners a great command of the language. However, flexibility in prose composition is essential and it’s always handy to have an alternative just in case you get stuck in an exam.
If you can’t precisely remember how to use these words then you could use the much simpler (but less impressive!) construction prohibeo (I prevent) + infinitive, e.g. prohibeo te fugere (I prevent you from fleeing).