4. indicating time

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(Prepositions)
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(Conjunctions)
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(Transition words for different purposes)
e.g.: 
a. subordinators: after, before, when, while, since, as, until, as soon as, by the time, once
b. transitions: first, second, next, then, finally, previously, now, presently, next, still, meanwhile, subsequently, afterward 
relevant: I-D-5

How to use first, next, last, after that, finally, etc.
source: ValenESL      
2010年2月12日

Prepositions of Time: by, until, by the time, no later than, earlier than...
source: English Lessons with Adam       2017年1月9日
http://www.engvid.com/prepositions-of...

whenever (as a subordinating conjunction)
source: LearnAmericanEnglishOnline       2017年4月30日

FINALLY, AT LAST, LASTLY and IN THE END
source: Crown Academy of English     2017年9月26日
IELTS complete course and writing corrections: https://goo.gl/5ffg8o

By or Until?
source: Learn English with Emma     2012年1月27日
quiz here: http://www.engvid.com/by-until/

Difference between “By” and “Until”
source: Learn English with EnglishClass101.com       2017年9月12日
https://goo.gl/CTqd9J

FOR, SINCE or AGO? Prepositions of Time 
source: Learn English with EnglishClass101.com       2018年3月13日

During / While / Meanwhile
source: Learn English with Papa Teach Me         2018年1月20日
Support the lessons on http://www.patreon.com/papateachme

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