Geography often plays a key role in determining who competed with whom. 
play a…role in: take a … part in 扮演…的角色, 起…的作用 
e.g. He plays the key/main role in the play. 他在该剧中扮演主角. 
His father plays a central role in his family. 
He played an important role in reaching the agreement between the two sides. 
双方达成一致,他起了很关键的作用. 

6. Instant interactivity is critical… 
e.g. instant noodle/ coffee/success 
*instantly,directly, immediately,the instance可以起连词的作用,相当与 as soon as. 
e.g. I send you the news instantly/the instant I got it. 
I will call you the instant I arrive in Beijing. 

7. adoption n. 采纳,接受 
adopt a child 收养孩子 
adapt oneself to 适应 
e.g. He found it difficult to adapt to the city life. 
You have to adapt to the life in college as soon as possible. 

8. lead to 指引,导致 
e.g. All roads lead to Rome.条条大路通罗马。 
His rumor led to great confusion. 他的谣言招致了极大的混乱。 
What led you to think so? 什么使你这么想。