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刷刷题刷刷变学霸
举一反三
【单选题】If those "mad moments"— when you can’t recall what your friend has told you or where you left your keys—are becoming more frequent, mental exercises and a healthy brain diet may help. Just as bodies r...
A.
everyone can be forgetful sometimes regardless of one’s age
B.
we can prevent our sound mind from aging with certain methods
C.
brain aging starts from the time when we are in our 20s and 30s
D.
memory loss is a sign that shows we are getting old
【单选题】维生素A
A.
临床上常用于治疗新生儿出血症
B.
临床上用于防治坏血病
C.
能发生硫色素反应
D.
结构中含有β-紫罗兰酮环
E.
本身不具有生物活性，进入体内后才能发挥作用