His sister had problems ________ her schoolwork at school.
A:on
B:at
C:with
D:in
观察下面一幅漫画,请以“司法体制改革”为开头,运用关联词“只有……才……”,写一段不少于30字的话,揭示漫画的内涵。
下列式子:x2,1a+4,3ab27,abc,−5x,0中,整式的个数是( )
t/s
0
5
15
25
35
n(A)/mol
1.0
0.85
0.81
0.80