"the ocean is a sink for carbon dioxide"
"He sank to his knees"
"The Japanese sank American ships in Pearl Harbor"
"He sank into nirvana"
"The raft sank and its occupants drowned"
"He sank into bed" "She subsided into the chair"
"The sun dipped below the horizon" "The setting sun sank below the tree line"
"The real estate market fell off"
"He slumped onto the couch" "My spirits sank"
"She sank her fingers into the soft sand" "He buried his head in her lap"
误 The sun was sinking down the west.
正 The sun was sinking in the west.
析sink作“下沉”解时已经含有“下”的意思,故不可再用down。