四边形ABCD的对角线AC、BD相交于点O,AD∥BC,AC=BD.试添加一个条件____,使四边形ABCD为矩形.
将x4﹣2x2+1因式分解的最终结果是____ .
⑴____A. Monday B. Day C. Sunday
⑵____A. Miss B. Music C. Mr
⑶____A. fat B. tall C. bag
⑷____A. tea B. egg C. milk
⑸____A. smart B. sugar C. short