细胞的动力工厂是（  ）

鸟类比鱼类、两栖类、爬行类动物复杂而高等，在繁殖上表现为（   ）

请阅读下面各小题，从方框中选择适当的短语填空，并将其序号填写到答题卷的相应位置。每个词语限用一次。

____ Lucy volunteers at a school. It’s ________for her because she wants to be a teacher.
____ —Let’s keep the secret between us .
—I won’t tell it to _________ .
____ ________ the policeman, the Blacks finally found their lost cat on the street .
____ —Who is that man ________ ?—He is the world champion we talked about just now .
____ Some old people have nothing better to do than to ________their unhappiness .
____ —I __________several times during the night .—What’s wrong  with you ?
____ —My company _______me _________a car .—Oh , you’re a lucky dog .
____ —I dropped my book on the floor . Could you please help me ________ it ________?—Wait a minute .
____ —How cold the weather is today !—Yes , and it’ll be even colder _________ .
____ Children can’t depend on their parents __________ .