10 today = 10 prepositons of time

Up to now (hasta ahora)  or so far ( hasta ahora, hasta aqui ) David has only been to Rome in Italy. Prior to going to Italy ( previous to / antes de, previo  ó anterior )   he had just been to other European cities, visiting friends. During the short the summer breaks ( durante = when an action happens), each time for two weeks  ( durante = how long an action happens for ), he had been working and then travelling, from July thru ( USA  = to )  August.  

Up  until /  up  to  1991 (  hasta ) he had had never flown and so far he must have taken dozens of flights to other countries. From time to time ( de vez en cuando = idiom) he travelled by train, using his student rail ticket,  but when he considered trips beyond 10 hours of travelling ( ore than = mas alla de )  he always looked for a cheap flight. After all, he was working throughout the week ( a lo largo de ) and wanted his hard earned cash to last a long time.

And  if you want to see more details , then just go here

http://lacstraining.files.wordpress.com/2012/01/1_prepositions-of-time2.jpg

Remember , if you want to check the full use of a word  then go to a good on-line dictionary .

e.g. Check how we use prior here http://dictionary.reverso.net/english-spanish/prior