题干

吞噬细胞对细菌的吞噬、加工处理和呈递过程如图所示.下列叙述正确的是(    )

A:吞噬细胞特异性吞噬细菌抗原

B:溶酶体参与抗原的加工处理过程

C:加工处理后的抗原可直接呈递给B淋巴细胞

D:抗原加工处理和呈递过程只存在于体液免疫

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B

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TaIL Spin

    Two dolphins race around in a big pool in the Ocean Park. The smaller dolphin Grace, shown off a few of her tricks, turning around and waving hello to the crowd. The most amazing thing about her, however, is that she's even swimming at all. She doesn't have a tail.

    Grace lost her tail as a baby when she got caught up in a fish trap. When the dolphin arrived at the Ocean Park in December 2005, she was fighting for her life. “Is she going to make it?” Her trainer, Abbey Stone, feared the worst. Grace did make it --- but her tail didn't. She ended up losing her flukes and the lower part of her peduncle.

    Over the past six years, she has learned to swim without her tail. Dolphins swim by moving their flukes and peduncle up and down. Grace taught herself to move another way---like a fish! She pushed herself forward through the water by moving her peduncles from side to side.

    The movement put harmful pressure on Grace's backbone. So a company offered to create a man-made tail for her. The tail had to be strong enough to stay on Grace as she swam but soft enough that it wouldn't hurt her.

    The first time Grace wore the artificial tail. She soon shook it off and let it sink in the bottom of the pool. Now, she is still learning to use the tail. Some days she wears it for an hour at a time, others not at all. “The tail isn't

necessary for her to feel comfortable,” says Stone, “but it helps to keep that range of motion(动作) and build muscles(肌肉).”

    Now, the dolphin is about to get an even happier ending. This month, Grace will star in Dolphin Tale, a film that focus on her rescue and recovery. Her progress has inspired more than just a new movie. Many people travel from near and far to meet her. Seeing Grace swim with her man-made tail gives people so much courage.