11) The subject of these lectures ----by the lecture committ

11) The subject of these lectures ____by the lecture committee.A) is announced B) have been announcedC) are announced D) has been announced12) I found an aspirin bottle ____dropped on the floor of David's room.A) was B) had C) had been D) is13)The goods ____when we arrived at the airport.A) were just unloading B) were just been unloading C) had just unloaded D) were just being unloaded14) If one ____by pride,he will reject useful advice and friendly assistance.A) overcomes B) is overcomeC) has been overcome D) overcome15) Most environment problems exist because adequate measures for preventing them ____taken in the past.A) was not B) were not C) were not being D) had not been16) You ought to have put the milk in the refrigerator,now ____sour.A) I smell B) it is smeltC) it smells D) it is smelling17) After the race____,the celebration began.A) had been won B) is wonC) will be won D)has been won18) He was here for a little while,but I don't knowswhereshe ____now.A) is B) was C) had been D) has been18) The young teacher has ____ competent.A) been proved to be B) proved to beC) been proved D) proved being19) Pluto,the outermost planet of the solar system,____photographically in March 1930.A) discovered B) was discoveredC) by discovery D) when discovered20) To get a better view of the stage,____.A)our seats had to be changed B) our seats were changedC) we had to change our seats D) our seats were changed by us