引起食品腐败的主要原因是______。
A.水分 B.微生物C.紫外线 D.氧
参考答案:B
Dorothy was always speaking highly of her role in the play, ____, of course, made the others unhappy.
A.who
B.which
C.this
D.what
绿化带应具有()功能。
A.防噪
B.防尘
C.水土保持
D.改善生态环境功能