The pickle (泡菜) jar as far back as I can remember sat on the floor beside the dresser (梳妆台) in my parents' bedroom. When he got ready for bed, Dad would empty his pockets and toss (投掷) his coins into the jar. It seemed that he was accustomed____doing such a thing When the jar was filled, I used to ____(go) with him and he would take the coins to the bank. “These are for my son's college fund. He'll never work at the mill (磨坊) all his life like me. If he ____ (work) like me in the future, he might not have a bright future. Good education can make a difference to people.” He had the coins ____ (count) and then he deposited the money in the bank.

    The years passed, and I finished college and took a job. Sometimes the job makes me tired ____(mental) but it is my particular preference. If possible, I will do it permanently in my life. Once, while ____ (visit) my parents, I noticed that the pickle jar in my parents' bedroom was gone. My father thought ____ very important for me to receive a good high education. He demanded that I ____ (try) my best to enter a good university.

    The first Christmas after our daughter Jessica was born, we made an ____(appoint) to visit my parents so we spent the holiday with them. Now our big family consists of five people. When Susan came back into the living room, she said softly, “Look”. To my amazement, there stood the old pickle jar, the bottom already____ (cover) with coins. I walked over to the pickle jar, dug down into my pocket, and pulled out a fistful of coins.

    With the strong emotion choking me, I dropped the coins into the jar. I looked up and saw Dad who was carrying Jessica. Our eyes locked, and I knew he was feeling the same emotions as I felt.

函数$f\left(x\right)=3\sin \frac{\pi }{2}x-{\log }_{\frac{1}{2}}x$的图象与x轴交点的个数是(   )

在2H₂+O₂2H₂O的反应中，H₂、O₂、H₂O的质量比为　____ 　，若要生成27g水，需要　____ 　g氧气和　____ 　g氢气才能恰好完全反应．