区域资源经济理论一般内容包括（）A、区位理论 B、区域经济发展理论 C、区位理论和区域经

A 21-year-old primigravida has an emergency cesarean delivery under general anesthesia because of unanticipated fetal distress. One postoperative intervention is to assist her to turn every 2 hours. Which of the following conditions is this intervention intended to prevent ？（）

A．Pressure ulcers.

B．Muscular stiffness.

C．Respiratory complications.

D．Venous stasis.

下列属于脊椎动物的是（　　）

A．蜻蜓

B．蚯蚓

C．蝗虫

D．家鸽

根据《招标投标法》的规定，投标保证金一般不得超过投标总价的( )。

A．0.5%

B．1%

C．2%

D．3%

树脂自硬砂可在（）内自行固化。

A.5min～10min

B.5min～50min

C.5min～100min

D.5min～150min

关井后（）min取准关井立管压力和套管压力及溢流量等数据。

A、15

B、5

C、4

D、2