以下人体体液组织中哪一种最少引起声衰减而且易产生显著的后方回声增强:
A．血液
B．胆汁尿液
C．脂肪
D．肝脾
E．肌肉
参考答案：B
母乳喂养的好处是（）
A.经济、省力、省时、方便
B.营养丰富、适合婴儿吸收
C.含有多种免疫物质，增强婴儿抗病力
D.增进母子感情
E.以上均是
A recent study by the Center for Economic Policy Research says that, in order to ease imbalances, the European Union needs to make changes while the United States has to spend more and save less.
