准备开井时，打开生产阀门时应注意什么？
参考答案：打开生产阀门时，应先缓慢打开一点通气，待生产阀门两端压力平衡后方可快速开启。
Our city has developed into a big city,which is______it used to be.
A．four times larger than that
B．four times the size of what
C．four times the size larger than what
D．as four times the size as that
与接触性皮炎相比，丹毒具有的特点包括（）
A.无刺激物或致敏物接触史
B.有发热等全身症状
C.境界明显的鲜红色水肿性斑片
D.皮疹为密集成片的红斑、丘疹及水疱
E.自觉瘙痒而无疼痛
