I think the safest mode of transportation is going by trainI think （ ）（ ）（）to travel is by train.I think （ the ）（safest）(way) to travel is by train.It's the safest and cheapest way to travel.它是最安全、最便宜的旅行方式。Flying is still considered the safest way to travel!空中旅行仍然被看作是最安全的旅行方式！