承诺给别人的是一份义务,给自己的则是一份期待。( )
下图中,____和____相同。
① ② ③ ④ ⑤ ⑥ ⑦ ⑧
关于物体的质量和物质的密度,下列说法中正确的是( )
A. My father is a teacher.
B. I'm very happy.
C. This is Lily's family.
D. My sister is very tall.
E. I am a student.