____the center of our planetary system was considered as heresy by the church in the Middle Ages.
B
【句意】太阳系的中心是太阳而不是地球这一事实被中世纪的教会认为是异端邪说。
【难点】That引导主语从句，全句的谓语是wasconsidered.
With one leg broken in that car accident, he cannot even walk, ____ run.
It’s necessary _________ us all to ________
Theradiois________astrangesignal.What’swrongwithit?
The first step in the study of any language is observing and ____ precisely what happens when native speakers speak it.