门牙不见了？

我还以为小孩子出牙，是由前面开始向后发展，所以婷婷突然间前面上下四颗未齐，就无端端在昨天长了第三颗大牙，就令我感到很奇怪也担心。后来上网搜寻一下，原来婷婷的出牙次序才不怪呢！

以下是我搜寻出来的其中一个资料。
Did you know that baby teeth have an order of appearance? I sure didn’t, until I found this picture here explaining how and when babies get teeth:

First of all the teeth appear in pairs. Pair numbered 1-1 comes first, then the pair numbered 2-2 and so on. There is also a time frame for teeth appearance: first four pairs erupt in the first year, pairs numbered 5 and 6 – from 12 to 18 months, pairs 7 and 8 – from 18 to 24 months and pairs 9, 10 after the baby is 2 years old.
摘自http://www.baby-log.com/my-baby-day-by-day/order-of-baby-teeth/

而我的婷婷目前的出牙次序有如下：-

原本还真担心怎么老虎牙还不长，就长大牙了？原来本来就因该是这样。可是，婷婷，你下排还有一颗门牙呢？不见了？