His sudden entrance took everyone by surprise.
他的突然出场使所有人都感到意外。
《牛津词典》The sudden entrance of the icy air through the broken window changed the particles of water into snow.
窗户被打破以后,冷风突然涌进大厅,湿热的空气中的水汽于是就凝成了雪花。
The non-symmetric refracted flow is possible to correspond to the non-symmetric entrance condition of upstream cross before sudden expansion section, and also to the symmetric entrance condition.
这种非对称折冲流动可能与上游突扩前断面非对称入口条件相对应,也可能与上游突扩前断面对称入口条件相对应。