① 57+310=310 ____ 57
② 38 ____ 56 =56 ____ 38
③ 13+59+49=13+ ( 59 ____ 49 )
④ 38+110+58+910= ( 38 ____ 58 )+( 110 ____ 910 )
A: And everyone has a locker (柜子).
B: What is it like?
C: What does it like?
D: Yes, twice a day.
E: Because I am studying at a new school.
F: I'm sure you will enjoy your new school life.
Sandy: Hi, Daniel. Why are you so happy?
Daniel: ____
Sandy: At a new school? Great! ____
Daniel: It's very big and nice. ____
Sandy: So you don't need to share a locker.
with your classmates, right?
Daniel: Yes.
Sandy: Do you do sports in your new school?
Daniel: ____ We do morning exercises and play ball games in the afternoon.
Sandy: ____
Daniel: Yes, of course. See you later.
某生物小组为了探究甲状腺激素对蝌蚪发育的影响,设计如下实验步骤:
a.取三个玻璃缸编号为甲、乙、丙,各加入500ml池塘水和等量的蝌蚪饲料;
b.在三缸中加入同时孵化的相同数量的蝌蚪(不少于5只),保持水温22﹣25℃;
c.处理方式和实验结果如下表:
组别
甲
乙
丙
处理方法
不做任何处理
破坏蝌蚪甲状腺
水中加入甲状腺激素
实验结果
正常发育成青蛙
停止发育
提前发育成苍蝇般大小的青蛙
读了《我是什么》,我知道了:自然界中水的特点和与人的关系。