黄酮类化合物结构中，2，3位碳间有双键者是
A．黄酮
B．黄酮醇
C．二氢黄酮
D．异黄酮
E．二氢黄酮醇
参考答案：A,B,E
关于节俭，你能够认可的说法是（）
A．节俭需因人而异，因个人或企业不同而有所区别
B．节俭绝不会促使企业增值，不应成为企业文化建设的内容
C．节俭是建设节约型社会的需要
D．会花钱才能挣钱，无须大力倡导节约
--- Can I have a talk with you at about 5 this afternoon, Mr．Smith?
--- All right, I ______ to my office from a conference then．I will be waiting for you there．
A．have come back
B．will come back
C．will have come back
D．will be coming back
