Inthepast50years,there_____agreatincreaseintheamountofresearch__
2023-11-03英语言文学 (军队文职)
Inthepast50years,there_____agreatincreaseintheamountofresearch_____onthehumanbrain.
A.was...did
B.has been...to be done
C.was...doing
D.has been...done
正确答案是D
