问题
选择题
煮沸过的水放凉后不宜用来养金鱼,因为这种水中几乎不含有( )
A.氧元素
B.氧原子
C.氧分子
D.水分子
答案
煮沸过的水中几乎不含氧气,氧气有氧分子构成,因为开水加热后氧气已经溢出,水沸腾很多气泡就是这个原因,即开水中几乎不含氧分子 那么煮沸过的水中也是如此,氧气溶解度很小;
故选C.
煮沸过的水放凉后不宜用来养金鱼,因为这种水中几乎不含有( )
A.氧元素
B.氧原子
C.氧分子
D.水分子
煮沸过的水中几乎不含氧气,氧气有氧分子构成,因为开水加热后氧气已经溢出,水沸腾很多气泡就是这个原因,即开水中几乎不含氧分子 那么煮沸过的水中也是如此,氧气溶解度很小;
故选C.
根据上文,填写下面家谱中所缺的职业或称呼,每空一词。 | ||||||||
My name is Jim. I have a big family. There are six people (人) in my family. My grandfather is a doctor. My grandmother is a nurse. They work in the same hospital (同一家医院). My father and mother are teachers in No.11 Middle School. My father teaches (教) Chinese, but my mother is an English teacher. Kate is my sister. We are new students in No.11 Middle School. My grandparents and parents like (喜欢) us and we like our family. We are very happy. | ||||||||
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