Bills are proposed legislation. 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.