_______Transportation_______ in Viet Nam is improving rapidly in terms of both quantity and quality. Significantly road  ______traffic_______ is growing rapidly, but the major roads are ______dangerous______ and slow to travel on due to outdated design and an inappropriate traffic mix. In recent years, the construction of expressways have accelerated. Air  ______travel_____ is also important for long-distance travel. Metro  _____systems______ are under construction in the two metropolises of Viet Nam, Hanoi and Ho Chi Minh City.