A:或
B:x|x≤1
C:x|x≥2
D:x|x≤0
如图所示是演示点火爆炸的实验装置.按动电火花发生器的按钮,点燃盒内酒精,盒盖被打出去.在汽油机工作的四个冲程中,与此能量转化相同的冲程示意图是( )
We all know that we’ll meet all kinds of difficulties in our lives in the future. We should learn to be ________ any challenge!
下列句子中加线成语使用恰当的一项是( )