As the New Year is coming, they ________ and celebrate together.
A:count down
B:take off
C:pick up
D:write down
要求:①语句通顺,字迹工整。②展开合情合理的想象。③表达自己的真情实感。④500字左右。
1 often take a bus to school, but I go to school by bike.
已知数列 {an}{bn}满足 a1=b1=1,an+1﹣an=bn+1bn=2,n∈N*,则数列 {ban}的前10项和为( )
如图表示某类酶作用的模型,请据图回答:
(1)该模型中A代表____,B代表____,C、D代表____ .
(2)若B代表麦芽糖,C、D则代表____ ;若B代表____ ,C、D则代表氨基酸;若B代表脂肪,C、D则代表____ .
(3)尝试用文字描述这个模型:____ .
(4)这个模型能解释酶的____ (特性).