—Mrs Zhang was sent to teach English in a poor mountain village last year.
—She said she would never forget some pleasant ___________ while working there.
A:experiments
B:expressions
C:experiences
D:emotions
已知双曲线与椭圆 x225+y216=1 共焦点,它们的离心率之和为 2110 ,则双曲线的方程是( )
如图示、在试管内装适量的水,用橡皮塞塞住,加热使水沸腾,根据图中提供的信息回答下列问题.
(1)酒精燃烧能量转化____
(2)塞子被推出的过程中,能量是转化的____
(3)塞子冲出试管后继续向前运动是因为____
(4)试管口出现白雾是____ 现象.