n. the main tower within the walls of a medieval castle or fortress
v. keep in a certain state, position, or activity; e.g., "keep clean"
v. retain possession of
v. look after; be the keeper of; have charge of
n. 生计, 维持, 保持
vt. 保持, 保存, 遵守, 看守, 整理, 维持, 履行, 经营, 拘留, 记帐
vi. 保持, 继续不断