A bloc is a coalition or group. Block means to obstruct, a large solid piece of work, stone or metal, or a pulley system. An event or someone can be centered at, centered in or centered on, but not centered around. Chaff means to ridicule good-naturedly, and it also means husks or rubbish. Site is a location.
Sight is a view or pertains to vision.
A car cannot collide with a telephone pole. Both words can be nouns or verbs. Composed means made up of. Speeches close or end. We are conscious of what we feel and aware of what we know.