蜜蜂与水螅可以属于同一类动物，这个类群是 (    )

A．软体动物

B．节肢动物

C．无脊椎动物

D．肠腔动物

In America．a friend's inviting you to a restaurant doesn't mean that he or she will pay for the meal     you are told in advance．

A．unless

B．if

C．although

D．until