单选题 Even our Mitsubishi four-wheel-drive truck gets altitude sickness once in a while , so we like to give her a rest whenever we can.

【正确答案】 A

【答案解析】[解析] sometimes“有时”；usually“通常”；often“经常”；seldom“很少”。划线单词once in a while“偶尔，时不时地”与sometimes词义相近，故本题选A。