Vitamin D helps our bodies make a special chemical, and this  special chemical, ____, affects

our brains, making us   feel happy.    

A. in turn                              

B. in particular    

C. in advance                              

D. in short

下列哪项不是肠梗阻的手术指征( )

A．不完全性肠梗阻

B．绞窄性肠梗阻

C．有腹膜刺激征或弥漫性腹膜炎征象的各型肠梗阻

D．肿瘤及先天性肠道畸形等不可逆转的器质性瘸变引起的肠梗阻

E．应用非手术疗法，经6～8小时病情不见好转