[解析]
46. B.由文中I am a student in No.14 primary school(小学).可知David是一名学生。故选:B.
47. C.由文中There are fifteen girls and eighteen boys in my class.可知David的班里有十八名男生。故选:C.
48. A.由文中He is tall and thin.可知王东是又高又瘦的。故选:A.
49. C.由文中He has short black hair and small eyes.可知王东的头发是黑色的。故选:C.
50. B.由文中He likes English,but I like maths.可知David喜欢数学。故选:B.