放置宫内节育器的并发症有_______、_______、______、_______、_______。
参考答案:子宫穿孔、节育器异位;感染;节育器嵌顿或断裂;节育器脱落;带器妊娠
— What did you do last weekend?
— I _________________________. [ ]
A. watered the flowers
B. play computer games
C. was very happy
按抽放与采掘时间关系不同,将瓦斯抽放方法分为采前抽放、采中抽放和()抽放。
A.本煤层
B.钻孔
C.巷道
D.采后