用方框那所给的单词或短语完成下列各句,注意形式变化
(1) Where was your mother? --She ____ .(2) Let's____ school by bus.(3)The twins like ____ .(4)____ is fun for the twins.(5) I ____ I'm late.(6) Don't ____ school next time.(7)What ____ with you? I'm____ ill.(8)____ do you go to the park? Once a week.(9)Where ____ you ____ ? Canada.(10) Look! Liu Mei____ .
(Ⅰ)求证:B1C1∥平面BCD;
(Ⅱ)求三棱锥B﹣C1CD的体积;
(Ⅲ)在线段BD上是否存在点Q,使得CQ⊥BC1?请说明理由.
可持续发展思想在中国源远流长,下列言论中蕴含可持续发展思想的是( )