—I hear Jack Chan will come to Laiwu next week.

—Really? ______ he comes, my younger sister will be very happy. [ ]

A．If

B．Until

C．Unless

D．Before

急性胸外伤中绝对必须进行紧急开胸探查的手术指征是：（）

A．胸内子弹留存

B．多根多处肋骨骨折合并血气胸

C．张力性气胸

D．气胸闭式引流后仍持续大量漏气