What did Columbus bring back on his second trip ？（）

单项选择题The reason why the toys most boys play with are different from those that girls play with is that （）.

A．their social roles are rigidly determined
B．most boys would like to follow their fathers’’ professions
C．boys like to play with their fathers while girls with their mothers
D．they like challenging activities

单项选择题According to the passage, Brazil has cut back its population growth （）.

A．by educating its citizens
B．by careful family planning
C．by developing TV programmes
D．by chance