c. inversion

IX. Sentence and ClauseTypesStructure, and Common Problems
Negative Inversion (with never, seldom, rarely, hardly, barely, scarcely, only, little)
source: Smrt English  2012-11-15
Exercise: http://smrtvideolessons.com/2013/07/2...

Complete Inversion
source: GrammarMadeClear  2011-4-19

Inversion and Emphasis
source: Niels Nielsen  2013-4-23

Inversion: "Had I known...", "Should you need..."
source: English Lessons with Adam  2014-4-2
quiz: http://www.engvid.com/english-grammar...

Inverted Sentences 
source: ESLEnglishFaby  2013-6-1

Partial Inversions after Negative Adverbials
source: iswearenglish  2011-3-27

source: aplangreyes  2011-11-13

Subject-Verb Inversions (with 'so', 'neither', 'seldom', 'not only' and 'no sooner', and also inversions in Conditional sentences)
source: Anglo-Link       2017年7月31日

Inversions (in conditional sentences, after no sooner, barely, rarely, etc. )
source: Your English Web         2016年7月9日

Inversion / for intermediate level and above
source: Practice English with Paul        2015年6月27日
04:31 inversion: exclamation
06:38 inversion: may
08:25 inversion: so/neither/nor
10:49 inversion after as/than/so
13:47 inversion: conditionals
16:38 inversion: adverbial expressions
21:15 inversion: descriptive writing
23:57 inversion: informal speech
25:40 inversion in reported story telling