诗歌鉴赏。
                                                                                                             田家
                                                                                                             郑獬
                                                                               田家汩汩流水浑①，一树高花明远村。
                                                                               云意不知残照②好，却将微雨送黄昏。
                                                                     【注释】①浑：这里是满的意思。②残照：夕阳。

看图，选词填空。

My sister isn't ____ her glasses.

She can't see the apples ____ the tree.

已知直线x+y=a与圆x²+y²=4交于A、B两点，且|$\overrightarrow{OA}$+$\overrightarrow{OB}$|=|$\overrightarrow{OA}$-$\overrightarrow{OB}$|，其中O为原点，则实数a的值为（　　）