总失真以（）为主。
A.电路热噪声
B.奇偶失真
C.量化失真
D.信道误码引入的失真
参考答案：A, C
He dressed himself quickly, _____ his schoolbag and went to school.
A．carrying
B．to carry
C．carried
D．carries
钻头钻孔呈多角形的原因是哪些，怎样防止？孔径尺寸大于规定尺寸，所产生的原因有哪些？怎样防止？
