A.don’t concentrate | B.hadn’t concentrated |
C.haven’t been concentrating | D.wasn’t concentrating |
A.runs | B.ran | C.is running | D.has been run |
A.has; worked | B.is; working | C.did; work | D.does; work |
A.had managed | B.managed | C.have managed | D.would manage |
A.hadn’t seen | B.haven’t seen | C.didn’t see | D.don’t see |
A.worked | B.was working | C.would work | D.would have worked |
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