单项选择题
A．essential B．available C．reliable D．responsible
A．If we focus our attention on one thing, we might forget another B．Memory depends to a great extent on the environment C．Reception helps improve our memory D．If we keep forgetting things, we’d better return to where we were
A．you may forget about the book you plan to buy B．you have to give up the best-selling book C．it makes you break your appointment D．it costs you too much money and time