在对切分孔型编号时，如“13H—QL12”，13H代表的是第13架轧机，QL12代表的是（）的螺纹钢的孔型。
参考答案：切分12
____________ her mother came to help her for the first few months ______________ to begin her project.
A．Only; she was allowed
B．Only after; she was allowed
C．Only after; was she allowed
D．Only; was she allowed
世界上人口居第一、二位的国家是（ ）
A．中国 美国
B．俄罗斯 中国
C．中国 印度
D．俄罗斯 美 国
