A:过氧化钠(淡黄色)
B:NO2(红棕色)
C:NO(无色)
D:铁锈(黑色)
Travelling to London
We think ⑴ is the best season to visit England.
We did most of our sightseeing(观光) ⑵ .
The best part of the trip was going to the theatre.
We don't think the English food is very ⑶ .
夏至日的日期大约是( )
复数z=x+3i1-i(x∈R,i是虚数单位)是实数,则x的值为( )