诊断肉瘤的主要形态依据（）
A.浸润生长
B.包膜消失
C.瘤细胞异型性明显
D.瘤细胞弥漫分布，与间质分界不清
E.血行转移
参考答案：D
Many workers were organized to clear away ________ remained of the World Trade Center.
A．those
B．that
C．what
D．where
用七条直线最多可画出几个不重叠的三角形( )
A．10个
B．11个
C．12个
D．13个
