①观察如图(a)、(b)或(c)可初步得出:吸管内的____振动,可以____.
②观察比较如图(a)、(b)和(c)可初步得出____.
春联能反映历史的变迁。下列春联能反映新中国成立的是( )
— Because he was always late for work.