—Please go and say hello to your aunt．She’s in the living room now．

—She has arrived! But when ______ she ______?

A．will; arrive

B．did; arrive

C．had; arrived

D．has; arrived

劳动合同是( )双务书面合同。

A．实践性的、有偿的

B．诺成性的、有偿的

C．实践性的、无偿的

D．诺成性的、无偿的