***的诗词是记载中国革命伟大历程的史诗。他的“军叫工农革命，旗号镰刀斧头，匡庐（泛指江西）一带不停留，便向潇湘（泛指湖南）直进”描述的是（ ）

在细胞工程—植物体细胞杂交中，需要将营养细胞的细胞壁除去，通常是采用纤维素酶和果胶酶的酶解破壁法处理。如将去掉了细胞壁的成熟植物细胞置于清水中，细胞将（　　）

    If you work hard to have a positive attitude, you might be surprised by how much better you feel about yourself and life in general. ____ The less stress you feel, the better you will feel generally. So if you've been feeling tired, think about the good, put on a happy face and you just might feel better soon.

    But how can you have a positive attitude when life is hard? It's more than just turning life's lemons into lemonade. ____ But it's worth it. Here are some ways you can develop and maintain(保持)a positive attitude even in the midst of life's troubles.

    ____It just means being an optimist and looking for the good in things, rather than being a pessimist(悲观者) and focusing on the bad in things. Sometimes your view can make all the difference in the world.

    Identify(确认) those areas of your life that might not be going so well. ____ Focus on one area at a time and think of ways you can find the positive in them.

    Smile and laugh! Yes, it can be that simple. Learn to love life, no matter what's going on. Smile at others and they will smile back at you.____Sometimes laughter really is the best medicine.

    Exercise！Get off the couch and get moving. Being active and healthy can give you a completely different attitude to life.

A. Have fun and find the humor in life.

B. You may find it hard to stay positive in your life.

C. Having a positive attitude can take some hard work.

D. A positive attitude doesn't mean taking no notice of life's troubles.

E. Having a positive attitude can also reduce your stress level.

F. These are the areas likely to make you think negative thoughts.

G. Go to bed earlier so you get the sleep you need to feel positive.

请阅读下列短文，从每题所给的四个选项(A、B、C和D)中，选出最佳选项。

A

    It was unusually quiet in the emergency room on December 25. I didn't think there would be any patients, sighing about having to work on Christmas. Just then five people showed up at my desk, a pale woman and four small children.

    “Are you all sick?” I asked doubtfully.

    “Yes.” she said weakly and lowered her head.

    But when it came to descriptions of their presenting problems, things got a little puzzling. Two of the children had headaches, but the headaches weren't accompanied by the normal body language of holding the head or trying to keep it still. Two children had earaches, but only one could tell me which ear was affected. The mother complained of a cough but seemed to work to produce it.

    Something was wrong, but I didn’t say anything but explained that it might be a little while before a doctor saw her. She responded. “Take your time; it's warm here.”

    I checked the chart after the admitting clerk had finished registering the family. No address---they were homeless. The waiting room was warm.

    I looked out at the family sitting close to each other by the Christmas tree. The little one was pointing at the television and the oldest one was looking at the decorations on the Christmas tree.

    I went back to the nurses' station and mentioned we had a homeless family in the waiting room. The nurses, complaining about working on Christmas, turned to sympathy for a family just trying to get warm on Christmas. The team went into action, much as we do when there's a medical emergency. Only this one was a Christmas emergency.

    We were all offered a free meal in the hospital cafeteria on Christmas Day, so we fetched that meal and prepared a large meal for our Christmas guests. Our team worked to meet the needs of a family who just wanted to be warm on Christmas Day.

    Later, as the family walked to the door to leave, the four-year-old came running back, gave me a hug and whispered, “Thanks for being our angels today.”