Yibin is one of the most beautiful ____in Sichuan．（　　）

This passage is very difficult．____people can understand it．（　　）

Look out!The food on the plate smells____．You can't eat it．（　　）

It's getting dark．You'd better ____out by yourself．It's dangerous．（　　）

We don't know if our friend ____．If he____，we'll let you know．（　　）