大全621

621.Scientists calculated that the asteroid, traveling at 46,000 miles an hour, is on an elliptical path that orbits the Sun once a year and regularly brings it back toward Earth.

(A) hour, is on an elliptical path that orbits the Sun once a year and regularly brings it

(B) hour, is orbiting the Sun once a year on an elliptical path that regularly brings it

(C) hour, once a year orbits the Sun, regularly bringing it on an elliptical path

(D) hour and orbiting the Sun once a year on an elliptical path, regularly bringing it（B）

(E) hour, orbits the Sun on an elliptical path once a year and that regularly brings it

答案是B，我想知道 is orbiting the Sun once a year，一年一次怎么可以用现在进行时呢？

请指教

首先，从定从的表达和其他考点上我们肯定可以排除其他选项，回过头我们分析B的时态，我是这样理解的，is orbiting表达这个asteriod也是最近一些年始终是orbiting the Sun once a year，或许以前或以后orbit the Sun once two years。

不是很好理解也，这样的题，再出现我可能还是会选错的，郁闷ing