才.....又.....means 1.just did it ,then do again quick. 2.just happened, then immediately turn back or another new thing happen. the structure is used to say the time between these two thing is very short，or u think it's very short. 1.. 好像才开始放假，马上又开学了。 u can omit 开始 and 马上，they are used to emphaize that u feel it's really very quick 3.我姐姐昨天才买一双鞋子，今天又买一双！ yes. 昨天and 今天 go before 才and 又. the time should come first in a sentence， 才and 又 here are adverbs describing the verb 买，so they should be right before the verb 4.他早上才去看电影，晚上又去看电影。 早上and 晚上 can be omit. but if u want to say he just did it in morning，then again in the evening， we use 早上and 晚上 to emphasize.（besides，it's the fact）And the second 电影 can omit.

1. 好像才开始放假，马上又开学了。 It doesn't change much when omitting "开始" here， the word "开始" is actually for emphasizing "starting" and you haven't done anything... But omitting 马上 will change the tense. "又开学了" means the semester "already started". To correct it, we need to add “要”, as it imply future tense. For example， 又要开学了 . Actually, 马上又要开学了 have the same meaning, here "马上" emphasize "soon it will " Skip both without changing meaning: 好像才放假，又要开学了。 2. we may put 才 before time or a verb. 才两点呢 （ it's just 2 o'clock!) 又两点了 （it's 2 o'clock again !) 才买 又买 But for your sentence, it's more natural to keep the original order。 我姐姐昨天才买一双鞋子，今天又买一双！ 4. Sure, it's grammatically correct to skip "早上" or "晚上". It just skipped some information. Skipping the noun at the end is OK ( and we always do :) ), but usually add "了". ...., 晚上又去看了。