苹果从枝头落下，不计空气阻力，这一过程中苹果的机械能变化情况是（）

读一读，回答下列问题。
    Betty is very happy because she moves to her new home today. Her new home is very big and nice. It has three bedrooms. The big one is for her parents. The small one is for her brother Paul and the middle one is for her. Betty likes pink，so her bedroom is a pink room. The walls are pink. The curtains(窗帘)are pink. The bed and wardrobe(衣柜)are pink, too. Every day, Betty does her homework in her bedroom. Betty's father likes the new home, too. He likes the study because it's quiet. He can read in it. Betty's mum likes the kitchen. It is big and clean. She can cook nice food for the family. Paul likes the new home because the living room is so big and he can play games with his friends there.

“高原之舟”是对（　　）的爱称．

阅读下面这两首宋词，完成文后题目。

（一）苏幕遮

周邦彦

燎沉香，消溽暑。鸟雀呼晴，侵晓窥檐语。叶上初阳干宿雨、水面清圆，一一风荷举。

故乡遥，何日去。家住吴门，久作长安旅。五月渔郎相忆否。小楫轻舟，梦入芙蓉浦。

（二）系裙腰

张先

惜霜蟾照夜云天。朦胧影、画勾阑。人情纵似长情月，算一年年。又能得、几番圆。

欲寄西江题叶字，流不到、五亭前。东池始有荷新绿，尚小如钱。问何日藕、几时莲。

用显微镜进行观察的材料必须是（    ）