牛瘤胃臌气的初期,可见到少量稀软的粪便。
参考答案:对
Though I have often heard this song ______, I have never heard you ______ it.
A.being sung; sang
B.sang; singing
C.sung; sing
D.to be sung; to sing
The mother, who is strict with her two daughters, has a clear list of ________ they are not permitted to do.
A.why
B.how
C.what
D.which