A：匀速上升的电梯里的乘客
B：石块抛入河中到落到水底之前
C：沿光滑曲面向下自由滑行的冰块
D：光滑水平面上，水平拉力作用下木块向前滑行一段距离
各大超市往往喜欢将新鲜的蔬菜用保鲜膜包裹起来，达到延长贮存时间的目的，这其中的主要原理是（ ）
No. 1 Middle School
Don't run in the hallways
Don't bring food into the classroom.
Don't listen to music in class.
You have to wear a uniform.
No. 2 Middle School
Don't bring food into the classroom
Don't wear a hat in class.
Don't go into the classroom without the teacher.
No. 3 Middle School
Don't listen to music in the classroom.
Don't run in the hallways.
You have to wear sports shoes for gym class.
下列各项中表述有误的一项是（ ）。
What kind of music does the boy like?
