________(fail)severaltimes,theyneedsomeencouragement.
Wewerebusy________(get)thingsreadyforthetrialproductionwhenhephonedus.
计算二重积分dDxy，其中区域D为曲线r1cos0与极轴围成.
设二次型f(x1,x2)=x12+4x1x2+4x22经正交变换化为二次型，求ab的值。
ShegotajobasanassistantstagemanagerattheCambridgeArtsFestivalTheatre,thinkingthatitmight________toacareerasaplaywright(剧作家).
