数位顺序表中每两个计数单位之间的进率都是10．

阅读下面短文，在空白处填入一个适当的词，或填入括号中所给单词的正确形式。

    Justin is a 16-year-old boy. He is thinking about how____(spend) his money during winter vacation. He ____(save) up about 300 dollars already. He plans to buy ____computer with his money but he also wants to go skating with his friends. He can't do both ____he doesn't have enough money. What should Justin do?

    We are often in these kinds of situations. You want to see a concert ____Saturday, but it is also your mother's birthday and you do not want to let____(she) down. In this case, you don't have enough time to go to both ____(place). You must make a decision. You must think about ____should be done first. You must consider the following questions ____(serious).

    ◆Which is more important?

    ◆Which decision needs my attention more?

    ◆Which choice would satisfy me more?

    After you've answered these questions, it may be much____(easy) for you to decide what to do. So the next time you must make a decision, remember to prioritize(优先考虑).

①最大值为 $\sqrt{2}$ ，图象关于直线x= $\frac{3\pi }{4}$ 对称；②在（﹣ $\frac{\pi }{2}$ ，0）上单调递增，且为偶函数；③最小正周期为π；④图象关于点（ $\frac{\pi }{4}$ ，0）对称，⑤在（0， $\frac{\pi }{4}$ ）上单调递增，且为奇函数．