When the students heard the good news, they jumped _______ in the classroom. [ ]

A. here and there

B. up and down

C. now and then

D. front and back

下列现象中，用做功的方法改变物体内能的是

A．冬天晒太阳感到暖和

B．酒精涂在手上觉得凉爽

C．用燃气灶烧水

D．双手搓搓感到暖和