– Can a plane fly _______ the Atlantic Ocean?–Yes, but it needs to go _______ the clouds for hours.
A:across, through
B:through, across
C:across, across
D:through, through
When the teacher got into the classroom, all the students stopped _______ at once.
在天平两端各放等质量的两个锥形瓶(瓶口用单孔塞和导管连接起来,气球中装有等质量的碳酸钠),如图所示。左盘锥形瓶中盛有M 克水,右盘锥形瓶中盛有M 克稀盐酸,天平平衡。