It has been widely accepted that only when the students take an active part in the class activities _______ the most effective.
People tend to love agricultural productswithout the use of fertilizers, pesticides or chemical additives.
It has been said that “happiness is like a butterfly, which, when __, is always beyond our grasp but which, if you will sit down quietly, may alight upon you."
_______ China views US-Japan relationship will have an effect on China’s military policy.
What our parents expect from us is going home and greeting them frequently, ________ giving them much money.
_______ by a great demand for environmental-friendly cars, those factories has produced more green ones.