The famous scientist was going out _____ he found himself surrounded by lots of young people.

The police said they would not give up looking into other possibilities ____they find out what happened.

_______ the paintings of da Vinci, the Louvre Museum has more than 6,000 other European paintings, _______ from the 13th century to the 19th century.

We should try every way to develop education,            it means slowing down in other fields.

The reason       he is late is    there was a breakdown on the railway．