Sam: Come on, it's time for school.
Mike: What class do you have today?
Sam: I have math, music and PE. How about you?
Mike: I have English, art and music.
Sam: I like English. What about you?
Mike: I like music.
选择正确的答案填在括号里。
它是红色的。可以说:
①加热前试管外壁的水没有擦干 ②加热时试管的底部触及灯芯
③被加热液体的体积超过试管容积的 13 ④加热时不停地来回移动试管
⑤没有进行预热,直接集中加热试管底部液体.