导游人员按职业性质可以将导游人员划分为专职导游和兼职导游两类
参考答案:对
有关地震波的叙述,正确的是[ ]
A、地震波是一种无线电波
B、纵波传播到古登堡面时完全消失
C、纵波和横波传播速度在莫霍面都明显减小
D、纵波传播速度快,而且可以在固体、液体和气体中传播
41.
Two types of stress:
Effects of stress--physical or emotional:
Guilty--useful, though most harmful:
Instances no need to feel guilty:
No one is perfect:
Life with a little stress--significant: