16.Jia Sixie's book is a practical g_________ to farming.

16.Jia Sixie's book is a practical g_________ to farming.
17.The Eiffel Tower is one of the most popular a______ in Paris.
18.She was taken to hospital with serious head _______(injure).
19.Have you seen Alvin’s stamp c______?
20.I’m tired of doing e______ housework every day.