--- How _______ is it from Xi'an to Dunhuang?--- It's less than 3 _______ flight.
- Dad. are you coming with us?- I'd love to, but something unexpected_______ in my company and I have to go.
When you take a plane, you_______ obey the rule to turn off your cell phone.
He was stopped when he tried to_______ on the queue.
My English teacher is very knowledgeable_______ she has been to many countries.
- What do you think of the traffic in our city?- It's_______ than it used to be, but there's still a long way to go.