收入差距扩大的人力资本因素有（）
A.个人能力
B.在职
C.家庭背景
D.正规教育的数量和质量
参考答案：A, B, C, D
(2013·辽宁六校高三联考)After walking on the zigzag path to the mountain top for a few hours, the tourists gathered under trees ________ shade and ________ down to have a rest.
A．provided; sit
B．providing; sitting
C．providing; sat
D．provided; sat
无害通过权
