根据所给的拼音填上恰当的字。
jià____子十足 局cù____不安
(Ⅰ)证明:PB∥平面AEC;
(Ⅱ)设二面角D﹣AE﹣C为60°,AP=1,AD= 3 ,求三棱锥E﹣ACD的体积.
—How about your school?
—Oh,very good.You can't find ________ one in this city.