【单选题】每秒内正弦量变化的次数称为频率,用f表示,单位是什么。
【简答题】A.He suffered from heart faiinre and (tied. B.He won three awards alter his death. C.His plays were writ-ten based on his own life. D.He was a victim of the American system.
【多选题】已知:x <- sample(1000, 100) 要对变量x的所有元素进行运算,下面程序语句符合R循环语法的是(仅循环语句部分):
A.
for (i =1; i<= 100; i++)
C.
for (i in 1:length(x))