下列关于免疫的叙述，正确的是[ ]

A．巨噬细胞吞噬外来细菌，必须有抗体参加   

B．B细胞和T细胞所含的基因不同，功能也不同   

C．先天性胸腺发育不全的患者，细胞免疫有缺陷   

D．记忆细胞的作用与外来抗原的多少有密切关系

Play is very important for humans from birth to death. Play is not meant to be just for children. It is a form of (1) that can tap into your creativity, and can allow you the chance to find your inner child and the inner child of others. I have collected the (2) of play here.
Play can stimulate you (3) . It can go against all the rules, and change the same (4) . Walt Disney was devoted to play, and his willingness to (5) changed the world of entertainment. The next time you are stuck in a (6) way of life, puI1 out a box of color pencils, modeling clay, glue and scissors, and (7) and break free. You will be amazed at the way your thinking (8) .
Playing can bring greater joy into your life. What do you think the world would be like if (9) each day in play I bet just asking you this question has (10) . Play creates laughter, joy, entertainment, (11) . Starting today, try to get 30 minutes each day to engage in some form of play, and (12) rise!
Play is known (13) . Studies show that, as humans, play is part of our nature. We have the need to play because it is instinctive and (14) . With regular play, our problem-solving and (15) will be in much better shape to handle this complex world, and we are much more likely to choose (16) as they arise. It creates laughter and freedom that can instantly reduce stress and (17) to our daily living.
Play can (18) , curiosity, and creativity. Research shows that play is both a "hands-on" and "minds-on" learning process. It produces a deeper, (19) of the world and its possibilities. We begin giving meaning to life through story making, and playing out (20) .