He does his (science) …………research in the laboratory.    

Bells have been in (exist) ……………for quite a long time.     

It is an (forget)…………. memory. I’ll remember it eternally.     

Every (participate)………. has made good preparations for the trip.     

You can buy things like saucepans in the (house) ………….store.     

The roof is too weak. It needs (strong)………...     

He may be successful one day; after all he’s very (ambition)……………. 

He is an (experience) ……………..worker because he is so young. 

My uncle is a (history)…………… . He knows a lot about Chinese history. 

Smoking is (harm)……………… to your health.