The size of the pupils and their response to light are controlled by the muscles of the iris, which is the colored part of the eye that surrounds the pupil. In...

美思雅，雅思考试通行全球。雅思考试是国际上最受欢迎的英语语言水平测试之一。在全球范围内，雅思考试被广泛使用以评估英语非母语人士的语言能力。雅思考试的成功建立与英国...