单项选择题 At each step along the way, economic pessimists warned that the economy was about ____ tumble into a yawning chasm.toC、 onD、 for

单项选择题 The growing spending _____ information technology can be taken as evidence that business is getting a payback on its investment.onC、 withD、 of

单项选择题 That _____ productivity paradox now seems to be over.callingB、 so-callingC、 so-calledD、 so called