彩神彩票
<tr id='ooixHI'><strong id='ooixHI'></strong><small id='ooixHI'></small><button id='ooixHI'></button><li id='ooixHI'><noscript id='ooixHI'><big id='ooixHI'></big><dt id='ooixHI'></dt></noscript></li></tr><ol id='ooixHI'><option id='ooixHI'><table id='ooixHI'><blockquote id='ooixHI'><tbody id='ooixHI'></tbody></blockquote></table></option></ol><u id='ooixHI'></u><kbd id='ooixHI'><kbd id='ooixHI'></kbd></kbd>
利用共振筛原理卐设计制作，能使学生直观生动地观察到受迫振动』和共振现象。
