把一根火柴梗平放在蜡烛的火焰中,约1s~2s后取出,能观察到( )
A.均匀地被烧黑
B.与外焰接触部分被烧黑
C.与内焰接触部分被烧黑
D.与焰心接触部分被烧黑
答案:B
Whatever achievements you have achieved, you should not be ______with them. If you ____, it is
unlikely that you will make further achievements. [ ]
A. satisfied; do
B. content; do
C. satisfied; are
D. contented; are
换流站常用抑制谐波的方法有哪些?