囊性和实性肿瘤的声像图之间相互比较包括（）
A.外形和边界
B.大小
C.内部回声
D.后方回声增强
E.侧边声影
参考答案：A, C, D, E
The view ______ many scientists hold is ______ too much emission of carbon dioxide is destructive.
A．what; that
B．that; which
C．that; that
D．which; which
处理键槽卡钻的原则是（），轻提转动，倒划眼，切匆大力上提。
A、上击下砸
B、上提
C、下砸下压
D、循环钻井液
