Time is the greatest discovery in the history of human beings.A．YB．NC．NG

听力原文：At what time is our fundamental research going to start？（A) I think the research

The error in a sextant altitude caused by refraction is greatest when the celestial body i

What does "the greatest discovery" refer to in the last paragraph？A．The purity of an unciv

As I am one of that sauntering tribe of mortals, who spend the greatest part of their time

It is said that the best time to visit the city i

听力原文:Man: I think this is the last time Im buying anything from that shop. I can be