痰、饮、水、湿同源而异流，其中最清稀的是（）。
A.痰
B.饮
C.水
D.湿
E.以上均非
参考答案：C
异位妊娠发病率约为（）
A.1‰
B.5‰
C.1％
D.2％
E.5％
The fans were very excited _______ David Beckham came to the show. [ ]
A. so
B. because
C. but
D. and
