语法填空
（1）This trend, which was started by the medical community（医学界）________ a method of fighting heart disease, has had some unintended side   effects  (effect) such as overweight and heart disease — the very thing the medical community was trying to fight.
（2）In 1863the first underground passenger railway in the world opened in London. It ran for just under seven kilometers and allowed people to avoid terrible __（crowds）__(crowd) on the roads above as they travelled to and _______ work.