吊机起升限位装置是防止（）发生事故。
A.扒杆过度起升
B.变幅过大
C.钩过度起升
D.以上三种
参考答案：C
—I think we can swim in that river.
—______. That's too dangerous. [ ]
A. I don't agree
B. I think so
C. Don't worry
D. You're right
实验中为什么要测定水的？
？