________ is often the case, we have worked out the production plan.

John shut everybody out of the kitchen ________ he could prepare his grand surprise for the party.

After months of voyage, Columbus arrived in ______ later proved a new continent．

—Nowadays the doctors are trying their best to reduce the people’s fear        they would be affected by the present disease called “Bird Flu （禽流感）”.

In his book,he explains both ______ it means to be a scientist and ______ science works.