已知f(x)在R上是奇函数,且满足f(x+4)=f(x),当x∈(0,2)时,f(x)=2x2,则f(7)等于 [ ]
A.-2
B.2
C.-98
D.98
答案:A
So excited were my classmates__________ the good result of the English speech competition!
A.to know
B.known
C.to be known
D.having known
常见的供漆装置形式()。
A.自流式
B.压力罐式
C.压力输送式
D.输送式