Books are a worthy invention of human history since they make it possible for us to make a

问题补充：

Books are a worthy invention of human history since they make it possible for us to make aof humans thoughts.

A. plan

B. sign

C. point

D. record

答案：

A. plan

B. sign

C. point

D. record

解析：名词辨析。A计划；B征兆；C点，意义；D记录。结合句意可知D正确。句意：书在人类历史上是一个非常有价值的发明，因为它让我们记录人类的想法变得可能。