在圆柱体外表面上的螺纹叫（）螺纹。
A.内；
B.阴；
C.外；
D.圆;
参考答案：C
一头猪重109.7千克，比一只羊的3倍还多3.2千克，一只羊重多少千克？（用方程解）
Though many extra trains and buses are used to carry passengers, traffic tools are still ________ needed during the Spring Festival.
A．badly
B．eagerly
C．equally
D．slightly
