上缘熔化度
参考答案：
上缘熔化度是确定切口上缘形状的尺寸。
As my dad are getting old, his eye-sight is starting to _______.
A．lose
B．fall
C．go
D．disappear
公司航班任一航段允许载运使用医用氧气的旅客数量载体宽体机不超过（）人。
A.1
B.2
C.3
D.4
