Millie is getting on well with her friends but she is a little selfish _____.
A:in time
B:on time
C:at times
D:at a time
如图所示的一组实验可用于研究燃烧的条件.下列说法错误的是( )
下列叙述中,正确的是( )
在三磷酸腺苷的结构简式A-P~P~P中,“A”代表( )
We look at them, and they look at _____.