题目

 --- When shall we meet your cousin at the airport?    --- His plane took off two hours ago, and it ______ arrive at five o’clock.   A. could                   B. should                      C. must                        D. can 答案：B我国西北地区发展农业生产最重要的限制条件是 A．土地资源不足     B．化肥、农药不足 C．劳动力不足       D．水资源不足