下列行为中,能够赢得他人尊重的是( )
A:拿别人的生理缺陷开玩笑
B:热情主动地帮助有困难的同学
C:喜欢传播他人的隐私
D:经常迟到和旷课
The first question is as as the second one. I can answer them easily.
骨含有比例适当的____和____,使骨具有一定的硬度和弹性,硬而不脆.