单选题 The last mayor was assassinated when he was fifty years old.

【正确答案】 B
【答案解析】题句中的画线词expire:过期,失效。可用选项B.cease to be valid,以词组对之进行解释。意为“不再有效。”辨义:A.cost more money花更多的钱;C.be mailed to the consulate寄到领事馆; D.be continued automatically自动继续。故答案为B。