Mark wants to buy a particular painting. He makes his request known to an art dealer who sells him the painting, providing him with a certificate guaranteeing the authenticity of the painting. Several months later, Mark has the painting valued and he is informed that the painting is a fake.Required:Advise Mark whether he may take action against the art dealer to invalidate the contract of purchase of the painting. (10 marks)

某女，27岁，妊娠39周，孕期检查正常，自然临产，宫缩强，胎膜刚破，突然出现烦躁，呼吸困难，发绀，最可能的诊断是

A．子痈

B．胎盘早剥

C．子宫破裂

D．羊水栓塞

E．前置胎盘