Originally Posted by jiang
1. He left rather than caused trouble. (Not OK)
1. He would rather run than walk. (OK. Comparative Adverb meaning, 'instead of' or 'a choice expressing a more likely alternative. Note the structure: rather Infinitive Verb than Infinitive Verb)
2. Rather than walk (to the store), he ran. (OK. Adverb; Note, rather than DO something - infintive verb e.g. DO, go, sleep, shop, etc.)
3a. Rather than cause trouble, he left. (OK, 'Rather than cause trouble' functions as an adverb phrase. It tells us the reason 'He left'.)
3b. He left rather than caused trouble. (Not OK; Comparative Adverb. 'left' and 'cause trouble', although both are verbs, do not pair semantically; they express a cause & effect relationship: He left because he did not want to cause trouble).
3c. He ran rather than walked (to the store, like he said he would). (OK. Comparative Adverb. Notice that 'ran' and 'walk' pair semantically).
All the best,