降尘的具体措施有煤层注水、（）、水封爆破水炮泥、（）、通风除尘和（）。
参考答案：采空区灌水；喷雾洒水；清扫落尘
Though the road covered with snow was very smooth, the old man smilingly ____ to be helped by others across the road．
A．refused
B．declined
C．accepted
D．promised
腹部膨隆可由哪种原因引起（）①巨大腹膜后肿瘤②过度肥胖③腹水④巨大卵巢肿瘤
A.①③
B.①③④
C.①②③
D.以上各项均是
