未知题型 Please be careful when you are drinking coffee in case you __________ the new carpet.A) crash B) polluteC) spot D) stain

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