地球表面五带的划分，下面四个地区有阳光直射的地区是（ ）
A：热带
B：北寒带
C：南寒带
D：北温带
世界上有两条著名的山系，一条是横贯亚欧大陆的____山系，另一条是由落基山脉和安第斯山脉组成的____山系．
Being happy is a skill that can be learned like a foreign language, and one way to ______ ourselves to be happy is to write down the little things that cheer us up each day.
