Alice____ ____her homework at home yesterday.
某些化学键的键能(kJ/mol)如下表所示:
键
H—H
Br—Br
I—I
Cl—Cl
H—Cl
H—I
H—Br
键能
436.0
193.7
152.7
242.7
431.8
298.7
366
已知三角形的三边分别为2,a-1,4那么a的取值范围是( ).
We should listen closely to the ____(直言不讳) criticism.
如图所示,当闭合开关S,且将滑动变速器的滑片P向左移动时,电磁铁( )