阅读下面的短文，从所给的单词中选择合适的单词补全短文，每空只填一词，每词只准用一次，注意书写工整。

   Sam ____ very sad last weekend. He was ill. He had a ____. His mother asked him to ____ in bed. He was very ____. Saturday afternoon, his good friends Tom and Mike came to see him. They ____a lot of fruit and some flowers for Sam. He was very happy.

   This weekend, Sam is going to go hiking ____ his friends. They are going to fly kites, ____ pictures and play football. Because Sam likes____ kites. Tom's hobby is ____ pictures. And playing football is Mike's____ sport.

下列函数中，既是偶函数，又是在区间（0，+∞）上单调递减的函数是（　　）

如图所示，两平行金属导轨间距l=0.5m，导轨与水平面成θ=37°．导轨上端连接有E=6V、r=1Ω的电源和滑动变阻器．长度也为l的金属棒ab垂直导轨放置且与导轨接触良好，金属棒的质量m=0.2kg、电阻R₀=1Ω，整个装置处在竖直向上的匀强磁场中，金属棒一直静止在导轨上．当滑动变阻器的阻值R=1Ω时金属棒刚好与导轨间无摩擦力．g取10m/s²，sin37°=0.6，cos37°=0.8．求：

春晚中的杂技节目《抖杠》令观众叹为观止，杂技演员一系列动作的完成都是（　　）

用显微镜进行观察时，若要转换物镜，需要调节（　　）