A、 Higher than one who lives in dull surroundings.
B、 Lower than one who lives in a boring environment.
C、 The same as one who lives in a normal circumstance.
D、 Undetermined yet by intelligence researchers so far.

【正确答案】 A

【答案解析】解析：选项A、B、C中的surroundings，environment和circumstance都有“环境”的意思，所以原文提到environment的时候就要留心。原文说在单调环境下生活的孩子比生活在丰富多彩环境下的孩子智力发展得少，故A正确，A中的dull是对原文中boring的同义替换。

A、 Most people are of similar intelligence regardless of background.
B、 People of the same blood type have similar intelligence.
C、 Family members usually have similar intelligence.
D、 Long-term partners tend to have similar intelligence.

【正确答案】 C

【答案解析】解析：原文说兄弟姐妹和父母孩子这类关系的人通常来说智力水平相似，这说明智力依赖血统，故选C。

A、 They will look more and more alike as time goes on.
B、 They will become increasingly dependent on each other.
C、 They might not realize their close relation at all.
D、 They might share a similar degree of intelligence.

【正确答案】 D

【答案解析】解析：原文说生活中相互亲密接触、但是并没有任何关系的人，很可能智力水平相似，故D正确。四个选项中只有D含有原文中出现频率最高的词intelligence，仅凭这一点也可以猜测它是正确答案。