黄酮类化合物大都显黄色，广泛存在于自然界，是一类重要的天然有机化合物。这类化合物多存在于双子叶植物及裸子植物中。苔类中很少含有黄酮，而藻类.微生物.细菌中没有发现黄酮类化合物存在。

黄酮类化合物的紫外光谱中，带Ⅱ为主峰；而带I很弱，常在主峰的长波方向处有一肩峰是（）

A.二氢黄酮

B.异黄酮

C.二氢黄酮醇

D.橙酮

E.黄酮醇

F.查耳酮

After a gastrectomy, the client will have a nasogastric tube in place for several days postoperatively. The nurse explains to the client that the nasogastric tube is for which of the following reasons

A. Prevent excessive pressure on suture lines.
B. Prevent the development of ascites.
C. Provide enteral feedings in the immediate postoperative period.
D. Enable administration of antacids to promote healing of the anastomosis.