A：How long________Mr．Smith________as an engineer？B：Since 1980．A.does，workB.has，workedC.did，workD.will，work
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B解析本题现在完成时也是表示一个从过去延续到现在的动作，不过是用since+动作的起点时间来表达动作的持续时间长度。(延伸)be动词的现在完成时和since或for连用时，是表示一个从过去持续到现在的状态，是现在完成时的第三种用法，如：He has been a Party memberfor five years．(since five years ago)．(他入党已经有五年了)(题型变化)Mr．Smith has worked as an engineer since 1980．(This is the year of 2005．)＝Mr．Smith has worked as an engineer for twenty-five years．(延伸)询问职业可以说：What does he work as？What does he do？What's his job？What's his profession？What's his occupation？