下列事例中,为了增大摩擦的是
A:拉杆旅行箱底部都装有轮子
B:向自行车的转轴处加润滑油
C:鞋底刻有凹凸不平的花纹
D:在气垫船底和水之间形成一层空气垫
I had a________experience yesterday.The brake of my electrical bike failed and I was very________then.
实验中,需要“加热约5mL(毫升)水至沸腾”,要用到的下列仪器是( )