The rover Opportunity is doing the following except ______.
A. It needs to search for life.
B. It needs to know where the water came from.
C. It needs to know where the water on Mars went.
D. It needs to make clear the state of the water on Mars.
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According to the passage, the formations on the surface of Mars could have been formed by
A. wind
B. volcanoes
C. earthquakes
D. water brought by comets
浮点数的表示范围和精度取决于________。
A. 阶码的位数和尾数的机器数形式
B. 阶码的机器数形式和尾数的位数
C. 阶码的位数和尾数的位数
D. 阶码的机器数形式和尾数的机器数形式
Which of the following is TRUE about nuclear?
A. Nuclear is cost efficient.
B. Nuclear is the alternative energy to oil.
C. Industrialized countries are not likely to build any new plant.
D. Industrialized countries will make a nuclear energy-development plan.
某碱液25.00 mL以0.100 0 mol·L-1 HCl标准溶液滴定至酚酞褪色,用去20.00 mL,再用甲基橙为指示剂继续滴定至变色,又耗了6.50 mL,此碱液的组成为()。
A. NaOH
B. NaOH+Na2CO3
C. NaHCO3+Na2CO3
D. Na2CO3