______ the warning message, more visitors might have been trapped in the flood.
A. Apart from B. Regardless of C. Other than D. But for
______ to sunlight for too much time will do harm to one’s skin.
A. After exposed B. If exposing
C. Having exposed D. Being exposed
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
