It is known that theory is based on practice and in turn serves practice.这句话的意思是什么,in turn在这里又是什么意思?

it is well known that _________to all is that Taiwan is the largest island in China.A.As is known B.As we know C.It is known D.What is known It is (wide) known that Ba Jin is one of the greatest writers in China . It is well-known that the Nansha_____（岛）is our country's in history.RT it's well known that zhou jiulun is a singger who is popular with the young It is known to all that mathematics is the basis of all other science. _______,the compass was first made in China.A.It is known to all B.We all know C.As is known to allD.Itis known that it is well-known __ all that China has the largest population of the world. 有关as is known to us all,it is known to us all 的辨析1.As is known to us all,the earth is round.2.It is known to us all that the earthe is round.3.what is known to us all is that the whale is not fish but mammal.请问这3个分别是什么从 英语翻译It is well-known that the English go out with an umbrella or a raincoat It is known to us that ______（贡献)to the development of computers in our country __is well known to all,the earth is round填as or it or that 改错It's known that Shanghai is the first largest city in China. It is known to all that the island belongs to China for___(century) It is well known that the wireless waves travel at very speed It is a well-known fact that the cat family embraces lions and tigers it is known to all that 和as is known to all that 区别 It ----- to everyone that the earth goes around the sunA.knows B.is known C.knowing D.is know