用人单位发生合并或者分立等情况，原劳动合同（）。

A.继续有效

B.失去效力

C.效力视情况而定

D.由用人单位自行决定是否有效

   __  it was hard for children to leave family and friends, many families chose to send their children

to America.    [ ]

A. Because

B. Although    

C. If    

D. As