题干
— Is Jack in the next room? — Well, it's hard to say. But I heard him ________ loudly when I passed by just now.
A：speak
B：to speak
C：spoken
D：speaking
答案(点此获取答案解析）
D
，月球表面附近没有磁场，那么，在月球表面上不能实现是（ ）