题目

 Stephen Hawking,        “the greatest genius of the late 20th century”, announced that there are really grey holes in the universe.          A. calling               B. to call         C. to be called           D. called 答案：D在高空飞行的子弹具有      能，      能，还具有      能，子弹落地后这三种能不为零的是      能。