If you meet Peter or John, tell ___ about the meeting.
A, them B,. him C. he D.they
______ 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 |