Which of the following provides the hard evidence that Mars was once a wet planet？
A. Schiaparelli
B. spacecraft
C. photographs shot from orbit
D. Martian rover Opportunity
查看答案
"Outlays" in the seventh paragraph is closest in meaning to ______.
A. taxes
B. money
C. incentives
D. tax increases
存款创造和收缩过程的原理相同，只是方向相反。()
A. 正确
B. 错误
Which of the following is NOT true about the "blueberries" on the surface of Mars？
A. They were scattered everywhere on the top of the rock.
B. They were scattered here and there through the rock.
C. They may have been formed by minerals that accreted in water.
D. They are actually the size of BB spherules.
Which of the following about solar power is NOT true？
A. It is cost inefficient.
B. It needs high technology.
C. Solar energy even cannot compete with wind.
D. Today's high oil prices make solar power commercially feasibl
微信支付 
支付宝支付