单项选择题
A．A doctor's notebook. B．A diary. C．A magazine. D．A school biology book.
A．Colds are always very dangerous. B．Colds are often unpleasant though not dangerous. C．Actually nothing can help get rid of colds. D．The best way to keep colds away is to be healthy.
A．People are more likely to catch cold in the winter. B．Colds are so common that even the strongest person cannot avoid it. C．Old people are likely to catch cold because they are unpleasant D．Colds can never be cured without the help of medicin