* The war had a ruinous effect on the country's economy. (This sentence emphasizes the destructive and damaging nature of the war.)
* His gambling habit was becoming ruinous, leading him to lose his house and savings. (This sentence highlights the devastating consequences of his addiction.)
* The company's decision to invest in that risky venture proved to be ruinous, leading to its bankruptcy. (This sentence shows how a poor decision can have a disastrous outcome.)
* The ancient temple was left in a ruinous state, its walls crumbling and its roof gone. (This sentence describes the state of decay and destruction.)
* The storm caused ruinous damage to the coastline, leaving homes and businesses in ruins. (This sentence depicts the extensive damage caused by a natural disaster.)
Remember, "ruinous" suggests something that is completely destroyed or seriously damaged, often leading to a devastating outcome.