Many a student __________ wearing MP3 players while walking on the street. It's quite dangerous. ( )
A:is used to
B:are used to
C:was used to
D:were used to
dònɡ jié
xǔ duō
shènɡ lì
suǒ yǐ
____
xiānɡ xìn
yè wǎn
duì fù
bài nián
i是虚数单位,计算1-2i2+i的结果为____ .