物质的性质决定物质的用途。下列因果关系不成立的是 ( )
A:因为磷燃烧能产生白烟,所以可用于制作烟幕弹
B:因为金属钨的熔点高,所以被用来制造灯泡中的灯丝
C:因为氮气化学性质不活泼,所以可用于食品包装袋内防腐
D:因为氧气能支持燃烧,所以可用作燃料
历史上把唐朝的全盛时期称为( )
如图是由几个相同的小正方体搭成的几何体的三视图,则搭成这个几何体的小正方体的个数是( )
If you want to be a better reader,what should you know about the speed(速度)of reading? Some people read very quickly,when others read very slowly. But which one is better? The quick reader may be a good reader when he reads a story-book for fun. But he may not be able to slow down to read instructions(说明书) carefully. The slow reader may be a good reader. But he may spend too much time reading a story for fun. So the reader who reads everything quickly or the one who reads everything slowly isn't really a good reader. Here are four things to remember about the speed of reading. Knowing why you are reading will help you to know whether(是否) to read quickly or slowly.Some things should be read slowly throughout. Examples(例子)are instructions for making or doing something. Math books,science and story-books are full of important information. You must read these things slowly to understand and remember every important idea. Some things should be read quickly throughout. Examples are stories for enjoyment,letters from friends,and some news from newspapers.In some of your reading,you must change your speed from fast to slow and slow to fast. You will need to read some pages quickly and then slow down and do more careful reading when you come to important ideas.