菊花茎尖→并放入取下培养基中培养→脱分化A→再分化B
选择合适的句子补全对话。
A. Yes,I did. B. We went there by bus.
C. How about you? D. I played baseball with John.
E. What did you do yesterday?
Amy:Hi, Tom ____
Tom:I picked apples on my uncle's farm. ____
Amy:____ How did you go to the farm?
Tom:____
Amy:Did you have a good time?
Amy:Me too.
读图，完成下列各题．
如图所示，长为L的细绳一端固定在O点，另一端系一质量为m的小球．开始时，细绳被拉直并处于水平位置，球处在与0点等高的A位置．现将球由静止释放，则它从A点运动到最低点B的过程中，重力瞬时功率的变化情况是（ ）
