劳动关系建立之日是（）
A.劳动合同订立之日
B.劳动合同履行之日
C.实际用工之日
D.劳动合同双方签字之日
参考答案：A
用于后牙基牙一类导线的卡环
A．单臂卡环 B．上返卡环 C．间隙卡环 D．正型卡环 E．下返卡环
The reason _____he was absent was _____ he was ill and unable to go to school.
A．which; that
B．why; because
C．which; because
D．why; that
