单项选择。
There ______ thirteen strawberries on the table. [ ]
A. is
B. are
C. have
D. has
答案:B
某药品原价每盒25元,为了响应国家解决老百姓看病贵的号召,经过连续两次降价,现在售价每盒16元,则该药品平均每次降价的百分率是______%.
什么是瓦斯压力?