(1)如图1甲、乙是两种声音的波形图,从图形可知: ____是乐音的波形图, ____是噪声的波形图;
(2)如图2所示,小华将一只正在发声的音叉触及面颊有震感,这个实验是用来探究 ____
A.声音产生的原因
B.决定音调的因素
C.声音能否在空气中传播
D.声音传播是否需要时间。
根据所学知识完成实验:
读诗《乞巧》《嫦娥》选择合适的解释。
A、 用云母做的屏风 B、 古代的节日,又名七夕 C、银河,天河 D、浩瀚无际的青天 E、今夜
今宵____
碧霄____
云母屏风____
乞巧____
长河____
Rick is a good man.He makes birthday cakes in a shop.His cakes are great and have very good prices,so many people buy his cakes.He makes friends with lots of his customers(顾客).They all like him very much.One evening.he wants to go home,but many of his old customers come in.Rick smiles(微笑)to them,“I am sorry.It is late today.If you need cakes,please come tomorrow.”One of them takes out a nice cake and says to him,“You make so many great cakes for us.This birthday cake is for you.Happy birthday, Rick.”