阅读下列短文，从每题所给的四个选项 （A 、B 、C  和 D ）中，选出最佳选项。

    My friend Jennie Crossen gave her bone marrow (骨髓) to a 51-year-old woman with leukemia, a woman she has never met.

    At the end of March, the Red Cross called back. Six different blood elements were tested; Jennie matched five completely and was about a 3/4 match of the sixth. So she was the best match.

    In April, Jennie went for a complete physical exam by one of the doctors who would perform the surgery. The doctor had to make sure that it would be no threat to her. The doctor told her that the surgery would entail having two quarts of bone marrow extracted from her hip bones. Jennie would probably be released the same day the surgery took place and should expect to be sore for a couple of months.

    "I didn't think it was that big a deal until I realized I was a match," Jennie said, "There wasn't a question in my head. It didn't seem like something that was going above and beyond."

    Jennie was left with two very small scars on her lower back from the surgery and was given medication to help dull the pain. She still felt a great deal of pressure on her lower back. "Being only 21, I feel like I am not old enough to significantly impact someone's life," Jennie said, "It seems strange to me that I could possibly save this woman's life which was being cut short by cancer."

    Three weeks after the surgery, Jennie received a call from the Red Cross representative who told her the transplant was successful. "I feel good, and I think it will actually work for her," she said, "So many people say they'd only donate if it was for a family member or close friend. This woman is someone's family and someone's friend. Obviously, no one she knows is a match, and the fact that you'd be able to help a perfect stranger is great."

结合语境，根据汉语提示用单词的适当形式填空。

用适当的介词或副词填空。

    Four Ways to Be a Great Roommate

    Having a roommate can be one of the best experiences in college or, easily, one of the worst.

           Follow these tips to avoid the common mistakes that turn good roommate relationships sour.

    Talk things out.

    Communication is key. If something happens, sit down with your roommate and have a face-to-face conversation. I've seen roommate relationships fall apart because something happens and, instead of talking to each other, the two start complaining about their roommates behind their backs.       

    Don't expect to be best friends.

    Some roommates become the best of friends, and some don't. Don't put pressure on yourself or your roommate, especially when you first meet.        And if your roommate doesn't end up being your best friend, don't worry.

    Ask before you take.

    This applies to food, clothes and anything else. If you want to keep a relationship going, show your roommate that you have respect for what is his or hers by asking first.            ◇Clean up after yourself.

    This should do without saying. Don't be lazy. Or, at least, don't bury your roommate in your clothes and garbage. Most people I've come across in college are messy.        But being considerate with where you put your stuff will help you avoid conflict.

A. So you need to think twice before you help your roommates out.

B. This creates nothing but awkward situations and unhappiness.

C. Even if you both agree to share everything, you should still ask.

D. You don't have all the time to clean your room and keep it organized.

E. It all starts with you to have a good relationship with your roommate.

F. Sometime you get stuck with someone who has tons of negative energy.

G. Remember, you're trying to make a new friend, not to scare your roommate away.