试题题干
Directions: Read each of the following sentences carefully, and choose A,B,C or D that has the closest meaning to the underlined word or phrase.
All plants and animals that have been studied carefully (including the human) seem to have built-in clocks.（）
参考答案
正确答案：
试题解析
internally fixed 内部固定的；built-in 内置的。
所有经过仔细研究的动植物（包括人类）似乎都有内置的时钟。