InAugust1977,asatellitetogatherdataaboutthe10millionblackholeswhicharethoughttobeintheMilkyWay.A.launchedB.waslaunchedC.hasbeenlaunchedD.islaunched
题目
InAugust1977,asatellitetogatherdataaboutthe10millionblackholeswhicharethoughttobeintheMilkyWay.
A.launched
B.waslaunched
C.hasbeenlaunched
D.islaunched