Complete the sentences with the given words in their proper forms (用括号中所给单词的适当形式完成下列句子):
In the city center you can seldom see ___________running in the street. (lorry)
We enjoyed ourselves very much on my grandma’s _________birthday yesterday. (eighty)
We will ___________ presents with each other at the Christmas party. (change)
Look! My father is lying in the sand ____________ to relax himself.  (comfortable)
It seemed that the boss was not very interested in the __________. (produce)
I’m afraid it was _________ of you to solve the problem in that way. (fool)
The washing machine is like an important _________ in my house. (service)
Our teachers always ___________ us to face difficulties bravely. (courage)