A:加成反应
B:取代反应
C:化合反应
D:分解反应
如图,抛物线 y=12x2+bx+c 与直线 y=12x+1 交于A、B两点,点A在x轴上,点B的横坐标是2.点P在直线AB上方的抛物线上,过点P分别作PC∥y轴、PD∥x轴,与直线AB交于点C、D,以PC、PD为边作矩形PCQD,设点Q的坐标为(m,n).
将人类的红细胞置于不同浓度的蔗糖溶液中,浸泡半小时之后的结果如图,依照细胞外形的变化判断蔗糖溶液的浓度,由高到低排列,正确的是( )
⑴What do you want to buy? ____ A. I see some buses and cars.
⑵What are the children doing?____ B. I want to buy a panda.
⑶What do you see on the street?____ C. Yes, she does.
⑷What colour is this table?____ D. They are reading books.
⑸Does she take a picture?____ E. It is brown.