单词拼写（共8小题；每小题1分，满分8分）
Sang Lan knew that the secret to happiness is to have a_____________（感激） for the good things in life.
My most v_________（清晰的） and happiest memories are those of school days.
My American friends are not ____________（熟悉） with that particular festival.
The UN assists thousands of v________（难民） of wars and disasters every year.
After graduation, many students are willing to r__________（偏远的） places in the west of China to work.
This text tells us about the e____________（演变） of video and sound devices.
Nowadays, most old people have medical i_____________（保险） in China, so they can see a doctor easily.
A ___________（典型的） mobile phone call is nearly always given greater importance than a face-to-face conversation.