考博考试

【单选题】 This passage deals mainly with ______.
A．the gravitational pull of the Earth and the moon
B．the factors involved in firing a rocket into the outer-space
C．the gravitational fields of the Earth and the moon
D．the speed and direction of a rocket traveling in the outer-space

网考网参考答案：A
网考网解析：
[解析] 综观全文，本篇文章主要是关于地球和月球的地心引力。因此A项为正确答案。 查看试题解析出处>>