在△ABC中,若各边的长度都扩大2倍,则下列关于tanA的说法中,正确的是( )
A.扩大2倍
B.扩大4倍
C.缩小一半
D.没有变化
答案:D
Red is usually_______danger so traffic lights include red ones. [ ]
A. marked with
B. lined with
C. related with
D. associated with
当烟囱高度一定时,烟囱抽力不因大气温度和季节的不同而产生变化。()