The following potential cash flows are predicted for maintenance costs for the Great machine: Year Cash flow Probability ($) 2 19,000 0.55 2 26,000 0.45 3 21,000 0.3 3 25,000 0.25 3 31,000 0.45What is the expected present value of the maintenance costs for year 2 (to the nearest whole number)?$

45#钢表示其平均含碳量为（）。 A: 45％ B: 0.45％ C: ＜0.45％ D: ＞0.45％

An Iowa paving project requires a water-to-cement ratio (w/c) of 0.45 in concrete due to exposure (freezing and thawing) condition, 0.50 due to sulfate content in soil and ground water, and 0.40 due to the concrete strength requirement. What should be the controlling w/c of the designed concrete? A: 0.45 B: 0.50 C: 0.40 D: 0.48

室外地坪相对±0.000标高（ ）m A: -0.3 B: +0.3 C: -0.45 D: +0.45

《冶金石灰》要求烧结用石灰S（）。 A: ＞0.45% B: ≤0.45% C: ≥0.20% D: ＜0.20%

下列式子错误的是（　　） A: 4.5×0.9＞4.5 B: 0.45×9.5＞0.45 C: 0.45+0.9＜4.5

优质碳素结构钢45，含碳量为（） A: 45% B: 4.5% C: 0.45% D: 0.45‰

底层平面图一般指（ ）所在标高的平面 A: -0.45 B: ±0.00 C: 0.30 D: 0.45

《冶金石灰》要求烧结用石灰S（）。 A: A＞0.45% B: B≤0.45% C: C≥0.20% D: D＜0.20%

欧洲标准二、三段奶粉蛋白质含量一般是( B )。 A: 0.45~0.8mg/100kJ B: 0.45~0.8g/100kJ