She wiped off the dust.
Billions of pounds were wiped off share prices.
He wipe the scribbling off the blackboard.
第一句的off是副词,那么二三句的用法是一致的wipe wth off sth我认为这里是不是应该将off认为成介词?词典把第三句放在了wipe+名词+副词的结构中,如果off不是介词那么后面怎么直接跟了the blackboard, 这里名词直接做状语?符合语法规范吗?请老师解答!