联营的原则是（）。

A.共同投资

B.共同经营

C.共担风险

D.共享利润

E.共同生产

A nurse performs cardiopulmonary resuscitation (CPR) for 1 minute on an infant without calling for assistance. In reassessing the infant after I minute of CPR, the nurse finds that he still isn't breathing and that he has no pulse. The nurse should then （）.

A．resume CPR beginning with breaths.

B．declare her efforts futile.

C．resume CPR beginning with chest compressions.

D．call for assistance.