钻井液出口流量传感器最关键部件是（）。
A、金属靶
B、滑动电位器
C、前置电路
D、信号电缆
参考答案：B
下列体细胞突变可能的后果错误的是()
A．动脉粥样硬化
B．衰老
C．遗传性疾病
D．致畸
E．致癌
I often laugh when I see my grandma learning pop songs. But she says, " One is
never _____ old to learn. " [ ]
A. too
B. so
C. very
D. quite
