Lessons can be learned to face the future, ________ history cannot be changed.
A.though B.as C.since D.unless
（2018·江苏）It’s strange that he _______ have taken the books without the owner’s permission.
A.would B.should
C.could D.might
Most of us, if we know even a little about where our food comes from, understand that every bite put into our mouths was ________ alive.
A.steadily B.instantly
C.formerly D.permanently
The failure was a big __________ to him, but he wasn’t discouraged and soon got as enthusiastic as ever.
A.blow B.issue
C.excuse D.factor
They believe that there are transport developments ______ that will bring a lot of changes for the better.
A.out of date B.out of order
C.around the clock D.around the corner
（2018·江苏）Try to understand what’s actually happening instead of acting on the _______ you’ve made.
A. assignment B. association
C. acquisition D. assumption
