Because little research had been done on the explanation of happiness, before going into the lab, Lyubomirsky had done some ______.
举一反三
- The homework when they left. A: did B: had done C: had been done D: has done
- The millions of calculations involved, ____by hand, would have lost all practical value by the time they were finished. A: had they been done B: they had been done C: having been done D: they were done
- The work_______by the time you get there. A: has been done B: had been done C: will have been done D: will be done
- We wish the work could ______ more quickly, but we'd had some difficulties in getting the right kind of supplies. A: have done B: have been done C: have been doing D: be done
- What had Alex done before he hung up? He had _______________. .