Once______ a difficult and even dangerous place______,Vietnam is now a friendly destination that welcomes visitors from all over the world.
She is American,__________she knows little about American history.
The science of medicine,__________progress has been very rapid lately,is perhaps the most important of all the sciences.
Information has been put forward__________more middle school graduates will be admitted into universities.
I read about it in some book or other,does it matter__________it was?
I still remember__________this used to be a quiet village.