（）误差是可以消除的。
A.系统误差
B.随机误差
C.过失误差
D.偶然误差
参考答案：A, C
The pianos in another shop will be________， but________.
A．cheaper；not as better
B．more cheaper；not as better
C．cheaper；not as good
D．more cheap；not as good
何谓栓子?常见的栓子有哪些?
