单选题 The henpecked man was still smiling ______ the door opened and his wife came in.
  • [A] when
  • [B] since
  • [C] because
  • [D] unless


【正确答案】 A
【答案解析】[解析] when表示前面的叙述所没有提到过的信息，意为“这时；突然”，句意为“他正笑着，这时门突然开了，他妻子走了进来。”