单项选择题
A．Seasonal differences in what mothers ate during pregnancy. B．Infection occurring at different times of the year. C．Its family background. D．Both A and B.
A．Teacher. B．Basketball player. C．Doctor. D．Engineer.
A．To go out for exercise. B．To go out for shopping. C．To go to the library to borrow a book on William Carlos Williams. D．To help the woman with her oral presentation.