Learning from _______ mistakes can help us stay cautious and make wise decisions in the days to come.

To work from home, which one could hardly imagine, has been made         with the development of computer technology. 

. Before radio and TV, music could only be heard _______, that is, you had to go to places where musicians gave performances.

— Jack has spent an hour in the shoe shop．Hasn't he decided which pair of shoes to buy?— Maybe．Young as he is, he is         about his appearance．

 Mothers love children, which is a(n) _______fact in spite of cultural differences.