化简$\left|\sqrt{2}-\sqrt{3}\right|$=____ 

    I have known my friend Rebecca for a long time．We first m____at a friend's birthday party five years ago．We found out that we both liked music，s____I asked Rebecca to come to my home one weekend．We listened to music together and soon became very good friends．We s____ almost every weekend doing homework and playing together．

    Three years ago．Rebecca's parents i____me to go on a holiday with them．It was great．We spent three wonderful weeks in a cottage(小别墅)n____a beautiful beach．Rebecca and I got up e____every morning．We loved walking along the beach in the morning．We took a lot of p____and had a lot of fun．

    Two years ago．I hurt my leg when I was learning to r____a bike and had to spend a week in hospital．Rebecca came to see me every day．But last year,Rebecca's father changed his job,and they m____to another town．Since then we haven't seen each other very much，but we have talked on the phone and we have w____emails to each other．

Sb₂O₅是一种重要的阻燃剂，工业制取该物质的化学方程式为：Sb₂O₃+2X═Sb₂O₅+2H₂O，则X的化学式为（  ）

骨骼肌战栗（俗称“大冷颤”）是人体对寒冷刺激的反应。此反射属于____ 调节。骨骼肌在反射弧中属于____ 。