A:5
B:6
C:7
D:5或8
分子、原子的主要区别是( )
如图所示的各种电路,同种元件的参数均相等,能利用滑动变阻器调节电灯从亮到熄灭的电路是( )
The doctor advised her to eat more bean products________meat which might be harmful to her heart.