下列所示物质的用途中,主要利用了其化学性质的是 [ ]
A.用活性炭做净水剂
B.用石墨代替部分导线到电路中
C.氧气用于医疗急救
D.用氢气流吹肥皂泡
答案:C
After _______ seemed half an hour, the teacher gave us the correct answer.
A.what
B.that
C.which
D.it
侧线器官是水栖无羊膜脊椎动物所特有的感觉器官。()