根据句意或首字母填入所缺单词。

1.  Don't worry! They arc living in s______.

2. A _______ some students, buses are not popular.

3.  This teacher is very popular a _______ the students.

4.  What's y _______  favorite transportation?

5.  Not many people can a _______ to buy a car.

上颌恒牙萌出时常见的顺序是（）

A.6-1-2-3-4-5-7

B.6-1-2-3-5-4-7

C.6-1-2-4-3-5-7

D.1-6-2-3-4-5-7

E.1-2-6-4-3-5-7