单项选择题
A．only remembers one of Jack's seventeenth birthdays B．always sends Jack something on his birthday C．has forgotten all of Jack's birthdays D．has forgotten Jack's seventeenth birthday
A．Scientists consider apes may drive trains some day. B．Apes have worked in some factories. C．Apes may one day be used to gather crops. D．An ape is not a large monkey.
A．who their trainers are B．they will be praised by their trainers C．they will get a reward D．something dangerous will happen to them