第14题: [单项选择]女孩,1岁。父母亲为表兄妹结婚,生后外表与常人无异,5月龄后头发渐变棕色;以后色更浅,眼珠在4个月后也由黑色变棕色,至今不能独坐,不会叫爸爸、妈妈;曾有过一次惊厥,尿味呈鼠尿臭,尿三氯化铁试验阳性。该病出现神经系统症状主要由于() A. 酪氨酸不足 B. 继发性肾上腺素不足 C. 生物蝶呤缺乏 D. 继发性甲状腺素缺乏 E. 高浓度苯丙氨酸及其旁路代谢产物对脑细胞的损害 参考答案:E
第21题: [单项选择]Questions 1 to 3 are based on the following conversation. According to the conversation, Zach A. takes too much time off from school. B. spends a lot of money on traveling. C. works very hard at school. D. doesn’t have much money to spend. 参考答案:C