维生素A缺乏症最早出现的症状是（）
A.皮肤干燥
B.暗适应差
C.角膜干燥
D.角膜软化
E.毛囊角化
参考答案：B
—Can you guess _______ ?
— I've no idea about it.
A. why was he late
B. when shall we have the sports meeting
C. how much he paid for the camera
【2】 是按照程序语句行的自然顺序，依次执行语句。
