Of all ___ reasons for my decision to go abroad, my father’s advice was ___ very important one.

In the experiment we kept _____ watchful eye on ______ developments and recorded every detail.

Four and________half hours of discussion took us up to midnight，and________break for cheese，chocolate and tea with sugar.                         (2013·大纲全国，33)

He came back on ___ and left on _____.

In most western countries on April Fool’s Day，people often play________ trick on each other；children especially have great________ fun.