Between 1918 and 1938, many new stations were constructed,__________ was designed by an architect named Charles Holden.
Scientists are trying to develop a special material, _______ they will make use of in space.
The education of _______young is always _______ hot and serious topic in modern society.
--- It shouldn’t take long to clear up after the party if we all volunteer to help. --- That’s right. _____________.
Mary: I think you should call Tom and say sorry to him. Ted: ! It was his fault.
Alec asked the policeman he worked to contact him whenever there was an accident.