①调节细准焦螺旋；

②转换高倍镜；

③把分裂中的细胞移至视野中央；

④将洋葱根尖永久装片放在低倍镜下观察．

正确的操作顺序是（    ）

下列的措施中，对保持生态环境最有利的是（   ）

    Kate's father took her to the hospital to see her one-day-old baby brother. They drove there straight from school. Kate had never been inside a hospital before.  ①This was a new experience for her.

    At the gate there was a large sign listing all the departments of the hospital, with arrows (箭头) showing how to find them. When Kate saw the A&E department(急救室), she asked,“What do those letters stand for?”“Accident and emergency,” replied her father,

②“Last spring, I took our sister there because she fell off her bike,”