1727, from broad (adj.) + -en (1). The word seems no older than this date (discovered by Johnson in one of James Thomson's "Seasons" poems); broadened also is first found in the same poet, and past participle adjective broadening is recorded from 1850.
权威例句
1. We must broaden our appeal.
我们必须进行更广泛的呼吁。
2. We'll broaden the discussion out in a minute.
我们马上要扩大讨论的范围。
3. a promise to broaden access to higher education
拓宽高等教育渠道的承诺
4. Let's broaden out the discussion to talk about education as a whole.