the purpose , the purpose of sth is to do sth.
the objective 目标
aim
goal
reason理由
function功能
intension意图
例：The function of Louis Sullivan's architecture was providing
A
large uninterrupted floor areas and to allow ample light into the interior.
B C D
分析：the function to provide, A错
例：The chief goal of biochemistry is for understanding the structure
A
and behavior of the carbon-containing compounds
B
that make up various components of a living cell.
C D
分析：the chief goal is to understand, A错
(5) 其他同根名词
ability to do 受到be able to 的影响
attempt to do 企图
decision to do 决定, 受decide的影响
ambition,
be ambitious to do
effort
例：For ancient people, myths were often attempts explanation
A B
catastrophic events such as volcanic eruptions.
C D
分析：B错，应改为to explain。 attempts后应跟动词不定式短语表目的，故将名词explanation改为to explain。
例：In the early 1960's the Civil Rights movement made great
A B
efforts for registering members of minorities to vote.
C D
分析：efforts to register, C错
C. 动词不定式的其他用法
(1) be to do 表示已安排好或者注定要发生的动作，属于将来时态的范畴
She and Anne are to meet at two o'clock.
(2)不定式的完成式为“to have done”，表示不定式的动作在谓语动作之前发生，这个完成式通常表示一般过去时
I am glad to see you.
I am glad to have seen your mother yesterday.
yesterday是一般过去时，修饰have seen.
(3) 形容词后面使用动词不定式，主动表示被动
It is difficult to decide.