A student told me that soon after he started his first job in Australia, his boss told him to ‘mop the floor’, and he stood there dumbfounded, because he didn’t know what ‘mop’ meant. His boss eventually told someone else to do it. I said that it was a good way of getting out of unpleasant work tasks. He said that if he did it too often he’d lose his job.
He said that ‘mop’ wasn’t in any of his textbooks, and he hadn’t encountered it otherwise. How do writers of textbooks decide which words to include and which to leave out? We can at least clean, sweep, mop, scrub or vacuum the floor (though we might vacuum the carpet or simply vacuum). Writers of textbooks can’t include them all.