直到近代人们才认识到发酵现象是由______引起的．

病史采集不包括（）。

A.主诉

B.患者系统疾病史

C.患者传染性疾病史

D.患者的修复治疗情况

E.患者的术后情况

科尔沁沙地原为肥美的科尔沁草原，处在农牧过度地带，由于人类不合理的活动造成固定和半固定的沙丘活化，使之成为今天的沙地。造成科尔沁草原土地沙化的最主要原因是                         

A．过度樵采

B．过度开垦

C．过度放牧

D．过度开采地下水

钛被誉为“太空金属”、“未来金属”。它的强度大、密度小、可塑性好、抗腐蚀性能强。它和它的合金被广泛用于火箭、导弹、航天飞机、船舶、化工和通讯设备中。室温下，它不与水、稀硫酸、稀硝酸反应，但易溶于氢氟酸，推断其原因是[ ]

A．氟离子易与钛离子形成可溶性难电离物质

B．氢氟酸的氧化性比其他酸强

C．氢氟酸的还原性比其他酸强

D．氢氟酸的酸性比其他酸强

阅读填空。

阅读短文，根据所读内容在文后1 ~10的空格里填上适当的单词或短语。注意：每空不超过3个单词。

     Good morning, everybody. My topic for today is "How Americans Value Time".

     Americans from childhood think a great deal about time and they learn to value time very much. As

children, they are taught.that time is everything.

     Time is money. A working American has to work hard for 8 hours a day or 40 hours a week. This is the

working time. In his spare time, he also works hard for more money. Even Saturday and Sunday are filled with

activities. In the street you can hardly see a man who walks slowly. They walk very fast. In fact, they are

running.

     Time is knowledge. No matter whether they go to work or go back home, they will take advantage of every minute to read on the buses, trains and ships.

     Time is friendship. When an American is invited to dinner, he won't be late or get there too early. Otherwise, his arrival will make the others unhappy.

     Seeing from above, we should learn from Americans to value every minute very much.

轮对须以同型号的车轴和车轮相组装，当车轮与车轴型号不同时，轮对型号以（）型号为准。

A.车轴

B.车轮

C.轴承

D.制动盘