It’s a difficult skill to master, but ______, it will benefit you for the rest of your life.
A. once obtained B. when to obtain
C. after obtaining D. while obtaining
My grandmother has kept the photo ______ she can see it every day for a couple of decades.
A. which B. when C. that D. where
Bob is in a hopeless situation, ______ we will keep a very close eye on.
A. which B. where C. that D. when
In the past decades, sea ice ______ in the Arctic as a result of global warming.
A. had melted B. has been melting C. melted D. is melting
I know you don’t like her, but try not to make it so ______.
A. curious B. obvious C. various D. previous
Schools in the north tend to be better equipped, ______ those in the south are relatively poor.
A. as B. unless C. when D. while
