When we visited my old family home, memory came ________ back.
A number of tests have been conducted to _________ that these drugs have no side effects.
---Why did Tom become wealthy this year? ---Because he sold _________________ he did last year.
Not until his father came back ____________ to bed.
The doctor said that maybe his disease is __________ the water he drinks.
It’s an agreement between towns or cities, _______ have similar features, such as industry, culture and entertainment.