【題目】Which "ex-" in the following words sounds different from the other three?

【題目】Keeping little pets helps us become more responsible people,________?

【題目】My parents lent me the money, _________I couldn’t afford the trip to Australia.

【題目】Look! Alice and Peter ______their sitting-room with flowers and balloons.

【題目】When talking to ladies, we should avoid _________their ages.

【題目】I tried to call to apologize to Mary, but she refused _______the phone.

【題目】I think one effective ______for me to improve my memory is to have enough sleep.

【題目】Peter always has smiles on his face, and he seems to be never angry _______other.

【題目】From now on , we have to reduce the air pollution and care ________our environment.

【題目】Somebody played _______trick on me by hiding my shoes under the stairs.