Windows的【画图】程序的左边绘图工具栏内有直接绘制（）的工具。
A.直线
B.三角形
C.椭圆
D.圆角矩形
参考答案：A, C, D
The time _________ I first spend with Nelson Mandela was a very difficult period of my life.
A． when
B． which
C． of which
D． at which
服务性运作比制造性运作的辐射范围广。
