(2013·北京西城区高三期末)Being more realistic，the elderly have learned to focus on things that make them happy and let go of that don't.
A. them
B. it
C. that
D. those
网友回答
A. them
B. it
C. that
(答案→)D. those
解析：句意：更现实的是，年龄大的人已经学会了集中精力于让他们感到高兴的事，并放弃那些不能让他们高兴的事。此处those＝things。