胸外伤后，出现胸壁软化，是因为（）。
A．单根肋骨单处骨折
B．相邻多根肋骨多处骨折
C．单根肋骨多处骨析
参考答案：B
______for a long time, but he tried his best to make up for what he missed.
A．Being ill staying in hospital
B．Having been ill staying in hospital
C．To be ill staying in hospital
D．He was ill staying in hospital
四川卧龙自然保护区是世界著名的孑遗动物、中国的国宝——大熊猫的集中栖息地。
