在图所示的内燃机工作的一个循环中,其四个冲程的顺序应当是
A:乙、甲、丁、丙
B:甲、乙、丙、丁
C:乙、丁、甲、丙
D:甲、乙、丁、丙
A. white B. orange C. pencil D. pen E. green
Hi, I'm Lucy. I have a pencil box. It's ____ I have a ____ It's black. I have an eraser. It's ____ I have a ____ It's red. I have a crayon. It's____
如图为动、植物细胞亚显微结构模式图,下列有关该图的正确叙述是( )