题目

 The airport ______ next year will help promote tourism in this area.       A. having been completed                           B. completed       C. being completed                                    D. to be completed 答案：D取一小块钠，吸干煤油，放在坩埚上加热，下列实验现象描述正确的是①金属钠先熔化②在空气中燃烧，黄色火花四溅③燃烧后得到白色固体④燃烧时有黄色火焰⑤燃烧后生成淡黄色固体A.①②③B.①②④C.①④⑤D.①②⑤