我国在21世纪新阶段的阶段性特征是提出科学发展观的现实基础。
参考答案：对
Learning curve theory emphasizes that in producing many goods, ______ .
A) cost decreases as production rates increaseB) average unit cost decreases as more units are producedC) materials become cheaper when they are purchased in bulkD) laborers become more productive because of technological advances
一台潜水泵在运行时，该井的动水位为25m，压力表指数为0.1MPa，泵管与泵座弯头的损失合计2.5m，计算该泵运行时的扬程？
