为了保证管环的（），每隔一段生产管片的时间，就应该进行管片的试拼检查。
A、长度
B、宽度
C、平整度
D、真圆度
参考答案：D
— What's the girl like?
— She was a brave girl. She fought bravely and her enemy had to _____ her at last. [ ]
A. give up
B. give up to
C. give in
D. give in to
了解胎儿肺成熟度（）。
A.羊水泡沫试验
B.羊水肌酐测定
C.羊水胆红素测定
D.羊水脂肪细胞出现率
E.羊水细胞学检查
