单选题 At last John Smith chose to step down as the company"s chief executive and return to his roots in software research.

【正确答案】 A

【答案解析】[解析] A项的意思是“辞职”与“step down”在本句表示的“离职”意思相近。B项“移动，搬走”；C项“退休”；D项“代替”。