but the fifteenth and sixteenth centuries are known(1) as the age of exploration because of (the dramatic burst of activity that(2) resulted in nearly quadrupling the known of extent of the world.)
1.are known 係五係passive voice?
2.括號那句點解?同埋句子只有一個verb 點解要加that?
3.括號句子為何寫成這樣?