【单选题】用相量表示正弦量,指的是用复数的模代表正弦量的( ),复数的辐角代表正弦量的( )
【简答题】What does the South Carolina Education Network do through beauty shops?
【简答题】正弦量的三要素是指正弦量的频率、幅值和( )。
【简答题】相量表示正弦量是指两者有对应关系,并不是指两者相等。为什么?
【单选题】What does the South China Tiger eat?
A.
It eats fruit and leaves.
B.
It eats other animals.
【简答题】配制0.25mol?L -1 的NaOH溶液100mL,某学生操作如下: ①用托盘天平称出1.00g氢氧化钠:将天平调好零点,再在两盘上各取一张同样质量的纸,把游码调到1.00g的位置上,于左盘放粒状氢氧化钠至天衡,取下称好的氢氧化钠,并撤掉两盘上的纸. ②把称好的氢氧化钠放入一只100mL的烧杯中,加入约10mL水,搅拌使之溶解,溶解后立即用玻璃棒引流将溶液移至一只100mL的容量瓶内,加水...
【单选题】What does the speaker say about the South American exhibition?
A.
It' s popular among children.
B.
It' s closed for cleaning.
C.
Lions and tigers are the features.
D.
It' s most recently built.
【多选题】正弦量的有效值相量表达式是指用复数的模表示正弦量的( ),用复数的辐角来表示正弦量的( )。