老张最近时常感觉腿疼,经医生检查后发现老张患了骨质疏松症,医生建议除药物治疗外进行食补.下面为4种食品所含营养成分的相对含量图,老张最好多吃的食品是( )
——I am going to take this summer holiday in Taiwan.
——Oh, really? Taiwan is ______ a beautiful island that ______ people in Guangdong go to visit it every year.
(l)图1中OA′是入射光线AO的折射光线,请在图中画出入射光线BO的折射光线OB′的大致位置.
(2)请在图2中标出通电后螺线管和小磁针的N极.
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