砂的概念是什么?
参考答案:
然岩石经自然风化或人工破碎,尺寸小于5mm的颗粒物统称为砂,按照矿物成分划分为石英砂、长面砂、石炭砂等数种。
D:阅读下面短文,从方框内选择恰当的句子填入文中空白处,使短文内容完整、意思连贯。
My life is always filled with sadness and little joy. 小题1:
Last year, I was allowed to enter the only key high school in my hometown. 小题2:
I rushed to my home and told my parents. But my father didn’t seem as excited as I was. He just kept smoking without saying a word and my mother put her head down and couldn’t help crying.
I knew very well what my family was like. My mum had been ill in bed for two years. We lived a hard life and I couldn’t continue my schooling. I felt so upset but I could say nothing to my parents. 小题3:
To my surprise, things completely changed before the beginning of the new term. My head teacher came to my family with some money, which had been raised by my schoolmates. He encouraged me, “Always have a dream. ” 小题4:I have been studying hard since I entered the high school. Whenever I meet difficulties, I always think of my teacher and schoolmates. I have a college dream and I must work hard for it, no matter how hard life is. Just as a great man says, “ 小题5: ”
李某,女,25岁,咳嗽、有脓性痰,并伴有胸痛;发热39℃;肺部闻及湿性啰音;WBC>13×109/L;青霉素皮试呈阳性。 根据李某病情的临床表现,可诊断为()
A.肺结核
B.社区获得性肺炎
C.支气管炎
D.哮喘
E.医院获得性肺炎