单选题 They want to know ______ do ______ us.
  • A. what can they... help
  • B. what they can... help
  • C. how they can... to help
  • D. what they can... to help
【正确答案】 D
【答案解析】[解析] what充当动词do的宾语，从句用陈述句。故应该选D。