HPLC测定醋酸地塞米松含量时,所用内标物质是
A.柯柏反应B.醋酸甲地孕酮C.己烯雌酚D.苯丙酸诺龙E.甲睾酮
参考答案:E
按括号内的要求把下列句子变一变。
1.You can find out about games on the computer.(对画线部分提问)
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2.She had fish and chips.(改为否定句)
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3.He taught Chinese five years ago.(改为一般疑问句)
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4.He read a book yesterday.(对画线部分提问)
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5.There is a bus in our city.(改为复数句子)
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先化简,再求值:已知:a的相反数是-2,|b|=3,且b<0.求:5(2a-b)-3(5a-2b+1)+(4a-3b+3)的值.