必须手术治疗的胃十二指肠溃疡并发症是
A．出血B．穿孔C．痉挛性幽门梗阻D．水肿性幽门梗阻E．疤痕性幽门梗阻
参考答案：E
According to the passage, which of the following offers most of the HDTV programmes so far
A．Retailer delivery services.
B．Cable providers.
C．Commercial television stations.
D．HDTV set manufacturers.
家长学校的主要任务就是联合所在学校、幼儿园、社区等教育单位或机构，为家长提供切实有效地指导服务。
