Young Club ____(found) two years ago to provide training for students and unemployed young adults aged 18 to 21.
用液态二氧化碳灭火器扑灭图书失火的原理是____
A.隔绝空气 B.降低图书的着火点 C.清除可燃物 D.____
如图,经过刨平的木板上的两个点,能弹出一条笔直的墨线,而且只能弹出一条墨线,能解释这一实际应用的数学知识是( )