五边形的内角和是( )
A:360°
B:540°
C:720°
D:900°
在正方体ABCD﹣A1B1C1D1中,下列几种说法正确的是( )
— Mabel, did you catch a cold again?
—Yes. I didn't realize the importance of doing enough exercise.
植物的组织培养技术是利用有性生殖的原理.(判断对错)