题目

The new dictionaries are very useful. They ________ well and ________ already . A. sell; have been sold out B. sold; had sold out C. sell; sell out D. are sold; have been sold out 答案：A 解析: “动词＋副词（well，easily，quickly等）”中的动词不必用被动式，这类动词有read，wash，sell，open，shut，clean，bum，pull，draw等。如图，圆锥的侧面展开图是一个半圆，求母线AB与高AO的夹角．参考公式：圆锥的侧面积S=πrl，其中r为底面半径，l为母线长．