_____ some mammals came to live in the sea is not known[ ]

I notice Linda is often absent from school because of illness. _______ she is not so healthy as she used to be?

They all say TITANIC is a goodmovie which is worth ______second time.

any problems when you arrive at the airport, give me a ring

I often see him working hard in his spare time. —________he has won the scholarship from time to time.