单选题 He is a (an) ______ and well-behaved child, but his parents worry about him for he talks too little.
【正确答案】 A
【答案解析】obedient顺从的；transient短暂的；conscious有意识的；神志清醒的；passionate充满热情的。后三个均不合题意。句意：他是个顺从、循规蹈矩的孩子，但他说话太少了，很让父母担心。