未知题型 Mr. Morgan can be very sad __________, though in public he is extremely cheerful.A) by himself B) in personC) in private D) as individual

未知题型 ___________ it or not, his discovery has created a stir in scientific circles.A) Believe B) To believeC) Believing D) Believed

未知题型 ______ one time, Manchester was the home of the most productive cotton mills in the world.A) On B) ByC) At D) Of