对婴儿来说，哪种氨基酸为必需氨基酸（）
A.组氨酸
B.胱氨酸
C.酪氨酸
D.精氨酸
E.牛磺酸
参考答案：A
解析：蛋白质主要由20种基本氨基酸组成，其中8种体内不能合成的氨基酸称为必需氨基酸（EAAs，异亮氨酸、亮氨酸、赖氨酸、蛋氨酸、苯丙氨酸、苏氨酸、色氨酸、缬氨酸）；对婴儿来说，组氨酸为必需氨基酸；早产儿肝脏酶活性较低，胱氨酸、酪氨酸、精氨酸、牛磺酸可能也是必需的。
| 根据对话的语境，补全对话，使对话内容完整。 | |
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A | |
| A: Are you going to be busy this evening? B: 1._____What's on your mind now? A: Hm,I was thinking of going to a movie tonight,will you come,too? B: 2._____ A: Will 5:30 be convenient for you? B: No problem. A: Stay at home. 3._____ | |
B | |
| A: Are you free tomorrow,Mr Black? I'd like to invite you to our English party. B: It's very kind of you. 4._____ A: I'm very pleased that you could come. Thank you very much. We will have a wonderful time. 5._____ B: I'll do my best to sing an English song. 6._____ A: The party will begin at half past seven. I'll be waiting for you in my home before seven. Let's go together. Is that all right? |