Jim records his physical training every time so that he can it and think about how he should improve it the next day.
A:contribute to
B:lead to
C:attend to
D:refer to
由图可知,大气中CO2浓度大约从1800年起急剧增加,下列解释合理的是()
如图为DNA分子的某一片段,其中①②③分别表示某种酶的作用部位,则相应的酶依次是( )
分式方程1﹣2xx-1=3x-1的解为( )