如下图实验，甲、乙、丙切去顶芽，丁顶芽不切除。将切下的乙顶芽立即放回原位置；将切下的丙顶芽放置在琼脂块上一段时间后将琼脂块置于丙原顶芽位置。四组枝条均给予图示单侧光照。下列对实验结果预测正确的是（   ）

看图，阅读短文，判断正误。

    Tommy is a boy. He is short and thin. He is 10 this year.

    Sally is his sister. She is 11. They go to school together.

    Tommy often gets up(起床) at 6:30 in the morning. He likes sunny days, He doesn't like rainy days.

    Tommy loves his mum. When he leaves(离开) home, he always says "Goodbye!" to her.

已知关于x，y的二元一次方程（a﹣1）x+（a+2）y+5﹣2a=0，当a每取一个值时，就有一个方程，而这些方程有一个公共解，试求出这个公共解．

青春总有烦恼，青春难免遇到挫折，但我们必须奋斗！青春不奋斗，不吃苦，还要青春干什么？