根据句意及汉语提示，写出句中所缺单词。
Mrs.Green drew two big________(正方形)on the blackboard.
In the________(沙漠)，water is very important.
This river is _______(深的)than any others in my town.
We don’t know why the ______(古代的)emperor built this temple.
Welcome to our short________(旅游)of London.