Noise makes it difficult to relax but quiet does not because the 
OPTIONS:
- quiet is soothing.
- noise is soothing.
quiet is soothing.

Kevin found running the marathon easier than Dennis. 
OPTIONS:
- Kevin had repeatedly meant to stop smoking.
- Dennis had repeatedly meant to stop smoking.
Dennis had repeatedly meant to stop smoking.

The airplane was steady, but the bus was shaky, because the 
OPTIONS:
- bus had a lazy mechanic.
- airplane had a lazy mechanic.
bus had a lazy mechanic.